Russian forces pounded targets in eastern and southern Ukraine with missiles, drones and artillery, Ukraine’s General Staff said on Monday, while millions remained without power in subzero temperatures after further strikes on key infrastructure.

In a flurry of weekend diplomacy, Ukraine’s President Volodymyr Zelensky spoke with the leaders of the US, France and Turkey ahead of planned Group of Seven (G7) and EU meetings that could agree on further sanctions on Russia.

There are no peace talks and no end in sight to the deadliest conflict in Europe since World War II which Moscow describes as a “special military operation” and Ukraine and its allies call an unprovoked act of aggression. Russia does not yet see a “constructive” approach from the US on the Ukraine conflict, RIA news agency quoted deputy foreign minister Sergei Vershinin as saying on Monday. The two countries have held a series of contacts in Turkey.

US President Joe Biden told Zelensky during a call on Sunday that Washington was prioritising efforts to boost Ukraine’s air defences, the White House said. Zelensky said he had thanked Biden for the “unprecedented defence and financial” help the US has provided. On the ground in Ukraine, Odesa on Monday resumed operations that had been suspended after Russia used Iranian-made drones on Saturday to hit two energy facilities.

Power is slowly being restored to some 1.5 million people, officials said. Zelensky said other areas experiencing “very difficult” conditions with power supplies included Kyiv.