Russian forces have intensified their offensive in eastern Ukraine ahead of the May 9 anniversary of the Soviet victory over Nazi Germany. Ukrainian troops are continuing stiff resistance.

Russia's defense ministry said its air force carried out missile attacks on 17 Ukrainian military facilities on Saturday. The ministry said strikes in the eastern region of Dnipropetrovsk destroyed a command post and a warehouse used to store rockets and artillery.

US and British defense authorities said Russia's advances in eastern Ukraine are slow in the face of Ukrainian resistance, and Russian units are likely suffering from weak morale.

Russian state-run media reported that the Russian currency, the ruble, was introduced from May 1 in some areas where Russia says it has taken control. These places include the southern region of Kherson and the city of Melitopol in the southeastern region of Zaporizhzhia.

In Nova Kakhovka, Kherson, the Russian military erected a statue of Soviet Union founder Vladimir Lenin.

The move appears to be an attempt to accelerate "Russification" by reminding people of the Soviet era, when Ukraine and Russia belonged to one country.

The Polish government announced that its army will carry out military exercises across the country for one month, starting on Sunday. Poland shares a border with Ukraine.

Russia is apparently wary about the Polish drills.

Russia accuses Poland and the US of planning to send Polish troops to Ukraine in the guise of a "peacekeeping mission".

Moscow has repeatedly criticized Western military support for Ukraine.

On Saturday, Hollywood actress Angelina Jolie visited Lviv in western Ukraine. She met children affected by the conflict and volunteers working with displaced people. At a railway station, Jolie told volunteers that children must be in shock.

Jolie is a special envoy for the Office of the UN High Commissioner for Refugees. But the Associated Press says she likely traveled to Lviv in her personal capacity.