Police officers detain a man in Novosibirsk on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Rostislav NETISOV / AFP)

Police officers are seen deployed in central Novosibirsk on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Rostislav NETISOV / AFP)

Police officers are seen deployed in central Novosibirsk on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Rostislav NETISOV / AFP)

Police officers detain a man in Novosibirsk on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Rostislav NETISOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a person in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a person in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a person in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers block a street in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a woman in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)

Police officers detain a man in Moscow on September 21, 2022, following calls to protest against partial mobilisation announced by President Vladimir Putin. - President Vladimir Putin called up Russian military reservists on September 21, saying his promise to use all military means in Ukraine was "no bluff," and hinting that Moscow was prepared to use nuclear weapons. His mobilisation call comes as Moscow-held regions of Ukraine prepare to hold annexation referendums this week, dramatically upping the stakes in the seven-month conflict by allowing Moscow to accuse Ukraine of attacking Russian territory. (Photo by Alexander NEMENOV / AFP)