The same day in May, Slon sent Pavan details of his flight from Moscow to Istanbul. According to the messages, Slon drove with Pavan to the bus terminal in Donetsk, where Pavan boarded a bus to Moscow. Pavan later told Polish police he was given $2,000 in cash before leaving Donetsk.

Ukraine hit the "bold target" of a microelectronics plant close to Moscow's city center, a Ukrainian official said on Thursday.

Foreign ministers from large European countries said on Thursday they were ready to step up pressure on Russia, "including through further sanctions" involving the energy and banking sector, to weaken Moscow in its war with Ukraine.

It is designed to make the West think a Kremlin victory is inevitable.

Russian forces have advanced into Dnipropetrovsk and Sumy regions, in fresh bid for Ukrainian land beyond what Moscow's already annexed.

The European Union announced a new package of sanctions against Russia on Tuesday, saying that Moscow’s daily deadly attacks against Ukraine show that it is not interested in peace – despite recent diplomatic efforts.

Lynne Tracy, the U.S. ambassador to Russia, will soon leave her post, her embassy said on Thursday, after serving through one of the most tense and difficult periods in relations between Moscow and Washington.

The Russia Day holiday marks the country's 1990 declaration of sovereignty, more than a year before the collapse of the Soviet Union.

Russia is exploiting and amplifying conspiracy theories that have appeared on social media about the immigration protests in Los Angeles, experts say.