Russian President Vladimir Putin has called on foreign volunteers to fight against Ukrainian forces.
At a meeting of Russia’s Security Council, he said those who want to fight Russia-backed forces should be allowed to come.
Russia’s Defense Minister Sergei Shoigu says there are 16,000 volunteers in the Middle East fighting alongside Russian-backed forces.
The volunteers may include skilled Syrian fighters, US officials say.
Russia is Syria’s longtime ally. Russian President Vladimir Putin is a key supporter of President Bashar al-Assad in the Syrian civil war.
Putin convened the meeting of the Russian Security Council after Russian forces began attacking new targets in Ukraine.
According to the BBC, Russia is targeting an airport and a fighter jet factory in Lutsk in northwestern Ukraine. An airport in the southwest also exploded. The bomber struck shortly after noon in front of a U.S. military base.
According to the Wall Street Journal, U.S. officials say Russia has recently been recruiting fighters from Syria. Russia hopes that the skills of these fighters in the city war will help in the destruction of the Ukrainian government and in the fight for control of the capital Kiev.