Ukraine's President Volodymyr Zelenskiy addresses French lawmakers via video lin, as Russia's attack on Ukraine continues, in Kyiv, Ukraine March 23, 2022.  Ukrainian Presidential Press Service/Handout via REUTERS
Ukraine's President Volodymyr Zelenskiy addresses French lawmakers via video lin, as Russia's attack on Ukraine continues, in Kyiv, Ukraine March 23, 2022. Ukrainian Presidential Press Service/Handout via REUTERS Reuters / UKRAINIAN PRESIDENTIAL PRESS SER

Western leaders meeting in Brussels on Thursday agreed to strengthen their forces in Eastern Europe, increase military aid to Ukraine and tighten sanctions on Russia whose invasion and bombardment of its neighbour entered a second month.

At an unprecedented summit of transatlantic alliance NATO, G7 rich nations and European leaders to address the continent's biggest military crisis since the 1990s Balkans wars, new battle groups were announced for four Eastern European nations.

The United States and Britain expanded sanctions blacklists. Various nations announced new military and humanitarian aid plus promises to take in refugees. And the EU was set to unveil steps to wean itself off Russian energy.

"We must ensure that the decision to invade a sovereign independent country is understood to be a strategic failure that carries with it ruinous costs for Putin and Russia," Canadian Prime Minister Justin Trudeau told the EU parliament.

Still, the pledges stopped short of President Volodymyr Zelenskiy's calls for a full boycott of Russian energy and a no-fly zone over Ukraine where Moscow's bombs are wreaking havoc.

Thousands of people have been killed, millions made refugees, and cities pulverised since Russian leader Vladimir Putin unleashed his invasion on Feb. 24.

"We ask for protection from (Russia) bombing us from the sky," said refugee Svetlana, 55, on her way back to Ukraine from Poland to rejoin family after initially seeking refuge.

"And help us not only with equipment but with peace forces and professional soldiers."

More than 3.6 million people have fled Ukraine since the invasion began, according to the United Nations. More than half of Ukraine's children have been driven from their homes.

COWERING BELOW GROUND

In the besieged southern port of Mariupol, which lies between Russian-annexed Crimea and eastern regions held by Russian-backed separatists, tens of thousands are hiding in basements with scant water, food, medicine or power.

In one part of the city captured by Russian troops, a patch of grass between charred hulks of blasted apartment buildings has become a makeshift graveyard. Freshly-dug mounds are marked with plastic flowers and crosses made from broken window frames.

Explosions sound in the background.

"It could have been me," sobbed Viktoria as she buried her 73-year-old stepfather Leonid, killed when the car ferrying him to a hospital was blown up 12 days ago.

Ukrainian officials accused Russia on Thursday of having forcibly deported 15,000 people from the city to Russia.

Moscow denies this.

In a month of fighting, Ukraine has fended off what many analysts had anticipated would be a quick Russian victory.

So far, Moscow has failed to capture any major city. Its armoured columns have barely moved in weeks, stalled at the gates of the capital Kyiv and besieging cities in the east.

They have taken heavy casualties and are low on supplies. Ukrainian officials say they are now shifting onto the offensive and have pushed back Russian forces, including north of Kyiv.

"In some sectors the enemy was driven back by more than 70 km (44 miles), in some sectors the enemy is at a distance of 35 km," said Defence Ministry spokesperson Oleksander Motuzyanyk.

Ukraine said its forces had destroyed the Russian landing ship the "Orsk" at the Russian-occupied port of Berdyansk.

Video footage, which Reuters confirmed was from Berdyansk, showed smoke rising from a blaze at a dock and the flash of an explosion. Russian officials did not immediately respond to requests for comment.

BIDEN COMES TO EUROPE

As U.S. President Joe Biden rallied allies on his first trip aboard since the war began, Washington announced latest sanctions against Russia, $1 billion more in humanitarian aid for Ukraine, and an offer to take in 100,000 refugees.

The Kremlin said NATO suffered from an "hysterical and inadequate" understanding of what is going on in Ukraine.

Zelenskiy, who has won admiration across the West for leadership under fire, urged people around the world to take to the streets in support of Ukraine.

"Come from your offices, your homes, your schools and universities, come in the name of peace, come with Ukrainian symbols to support Ukraine, to support freedom, to support life," he said in a video address.

Ukraine's armed forces chief of staff said on Thursday Russia was still trying to resume offensive operations to capture the cities of Kyiv, Chernihiv, Sumy, Kharkiv and Mariupol.

In Mariupol, satellite photographs from commercial firm Maxar showed massive destruction of what was once a city of 400,000 people, with apartment buildings in flames.

Journalists have not been able to report from inside the Ukrainian-held part of Mariupol for 10 days, during which time Ukraine says Russia has bombed a theatre and an art school being used as shelters, burying hundreds alive.

In the Russian-held part of the city, trucks arrived with food supplies in cardboard boxes bearing the "Z" logo that has become the Russian symbol of its "special operation". Hundreds of people, many elderly, emerged from surrounding ruins, queuing mostly in silence as men in Russian emergencies ministry uniforms distributed boxes.

Angelina, a young mother-of-two, said she had received bread, nappies and baby food. "It's difficult to leave by bus now. We hope the number of people trying to get out will go down and it will get easier for us to leave," she said.