KYIV/LVIV, Ukraine (Reuters) – U.S. President Joe Biden sought to prevent Beijing giving new life to Russia’s invasion of Ukraine in a video call with his Chinese counterpart on Friday as stalled Russian forces pressed on with bombardments of towns and cities.

With Russia looking to regain the initiative, three missiles landed at an airport near Lviv, a western city where hundreds of thousands thought they had found refuge far from Ukraine’s battlefields.

The Russian defence ministry said it was “tightening the noose” around the besieged southern port of Mariupol, where officials said more than 1,000 people may still be trapped in makeshift bomb shelters beneath a destroyed theatre.

Ukraine said it had rescued 130 people from the theatre’s basement after the building was flattened by Russian strikes two days ago. Russia denied hitting the theatre and says it does not target civilians.

China is the one big power that has yet to condemn Russia’s assault, and Washington fears Beijing may be considering giving Moscow financial and military support, something that both Russia and China deny.

“The Ukraine crisis is something that we don’t want to see,” Chinese state media quoted President Xi Jinping as saying in the call, which they said was requested by the U.S. side.

NATO should hold talks with Russia to resolve the factors behind the conflict, Chinese state media quoted Xi as saying, without assigning blame to Russia for the invasion.

The White House said only that the two men spoke for just under two hours. Earlier, U.S. Deputy Secretary of State Wendy Sherman said Xi should tell Russian President Vladimir Putin to end “this war of carnage” in Ukraine.

‘MINIMAL PROGRESS’

At the start of the fourth week of Putin’s attempt to subdue what he calls an artificial state undeserving of nationhood, Ukraine’s elected government is still standing and Russian forces have not captured a single big city.

Putin promised tens of thousands of people waving Russian flags at a soccer stadium in Moscow the “special operation” would succeed.

“We know what we need to do, how to do it and at what cost. And we will absolutely accomplish all of our plans,” Putin said, adding that, when needed, Russian soldiers “shield each other from bullets with their bodies like brothers”.

State television briefly cut away from his speech in mid-sentence; Kremlin spokesman Dmitry Peskov said later the interruption was due to a technical fault.

Russian troops have taken heavy losses while blasting residential areas to rubble, sending more than 3 million refugees fleeing over Ukraine’s western border.

Ukraine said its troops had prevented their Russian adversaries from making any fresh advances on Friday and the Russians had problems with food, fuel and communications.

Britain said Russian forces had made minimal progress this week. “Ukrainian forces around Kyiv and Mykolaiv continue to frustrate Russian attempts to encircle the cities,” the UK defence ministry said.

Jakob Kern, emergency coordinator for the crisis at the U.N. World Food Programme (WFP), said Ukraine’s “food supply chain is falling apart. Movements of goods have slowed down due to insecurity and the reluctance of drivers”.

Oksana Zalavska, 42, fled Mariupol two days ago after staying in an overcrowded bomb shelter where adults ate one tiny meal a day as rations were low.

“Now I know everything about starvation in 2022,” she said.

WFP buys nearly half of its wheat from Ukraine to feed people in global crisis zones. Kern said the war has already driven global food prices to all-time highs, and could cause “collateral hunger” in poor countries worldwide.

INTENSE SHELLING

Russia has been intensively shelling eastern Ukrainian cities, especially Chernihiv, Sumy, Kharkiv and Mariupol.

Troop columns bearing down on Kyiv from the northwest and east have been halted at the gates of the capital by fighting. But residents have endured nightly deadly missile attacks.

Debris from a missile blew a large crater in the ground in the middle of a residential block where a school was also located in northern Kyiv, shattering hundreds of windows and leaving debris scattered around the complex.

At least one person was killed, emergency services said. Kyiv’s mayor said 19 people were injured including four children.

“This is a war crime by Putin,” said Lyudmila Nikolaenko, visiting her son, who lived in one of the apartments hit. “They say they aren’t hitting regular people, they say we are firing at ourselves.”

In Mariupol, some 400,000 people have been trapped for over two weeks, sheltering from heavy bombardment that has severed supplies of electricity, heating and water, local officials say.

Donetsk region Governor Pavlo Kyrylenko said around 35,000 people had managed to leave the city in recent days, many on foot or in convoys of private cars, but near-constant shelling was preventing humanitarian aid from getting in.

French President Emmanuel Macron told Putin he was extremely concerned about the situation in Mariupol while the Kremlin said it was doing everything possible to protect civilians.

BIDEN PUTTING PRESSURE ON BEIJING

Kyiv and Moscow reported progress in talks this week towards a political formula that would guarantee Ukraine security protection outside of the NATO alliance.

But Ukraine said the need for an immediate ceasefire and withdrawal of Russian troops remained unchanged, and both sides accused each other on Friday of dragging out the talks.

With sanctions cutting Russia off from advanced economies, China is Russia’s last big economic lifeline. Putin and Xi signed a “no limits” friendship pact three weeks before the invasion which repeated some of Russia’s grievances over Ukraine.

China has so far been treading a careful line, abstaining in votes over U.N. resolutions condemning Russia.

Hours before the phone call, China sailed an aircraft carrier through the sensitive Taiwan Strait – shadowed by a U.S. destroyer – a person with direct knowledge of the matter said.

(Reporting by Reuters bureaus; Writing by Peter Graff and Philippa Fletcher; Editing by Tomasz Janowski, William Maclean and Cynthia Osterman)

PHOTO: A Ukrainian service member checks cartridges for a machine gun at a position on the front line in the north Kyiv region, Ukraine March 18, 2022. REUTERS/Gleb Garanich