Policemen detain an ultra-right activist after clashes with pro-Russian supporters at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky), APTOPIX

An ultra-right activist is sprayed with tear gas during clashes with pro-Russian supporters, at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

Ultra-right activists fight with pro-Russian supporters at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

An ultra-right activists fights with pro-Russian supporters at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

Policemen detain an ultra-right activist after clashes with pro-Russian supporters at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

Ultra-right activists fight with pro-Russian supporters, at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

A Soviet army veteran holds his hat that ultra-right activists covered in red paint, at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

An ultra-right activist pours red paint on the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

Soviet army veterans talk with an ultra-right activist, at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)

Ultra-right activists fight with pro-Russian supporters, at the Soviet-era monument to General NIkolai Vatutin in Kiev, Ukraine, Friday, April 13, 2018. Activists of the Right Sector group on Friday splashed red paint on the Soviet-era monument to Nikolai Vatutin, a Red Army general who died in fighting during WW II. They also engaged in scuffles with supporters of an opposition party who attempted to put flowers to the monument in the Ukrainian capital, Kiev. (AP Photo/Efrem Lukatsky)