Zelensky warns NATO as Russia strikes near Polish border

Ukrainian President Volodymyr Zelensky warned NATO Monday that its member states would soon be attacked by Russian forces after an airstrike hit a Ukrainian military base close to the Polish border.

Meanwhile, the death toll in the strategic southern port city of Mariupol, facing acute deprivation amid a prolonged siege, has topped 2,000, officials there said.

While western Ukraine has largely been spared so far, Russian air strikes overnight Saturday into Sunday carried the war deep into the west, killing 35 people and wounding 134 at a military base near Yavoriv, outside the city of Lviv -- which is dangerously close to the frontier with EU and NATO member Poland.

"If you do not close our sky, it is only a matter of time before Russian missiles fall on your territory, on NATO territory, on the homes of NATO citizens," Zelensky said in a video address released shortly after midnight, urging NATO to impose a no-fly zone over his country. 

Washington and its EU allies have sent funds and military aid to Ukraine and imposed unprecedented economic sanctions on Russia.

Zelensky has continued to implore foreign counterparts to do more.

"Last year, I clearly warned NATO leaders that if there were no harsh preventive sanctions against the Russian Federation, it would go to war," Zelensky said. "We were right."

Further east, the latest fighting in Kyiv's suburbs left a US journalist dead -- the first foreign reporter killed since Russia's invasion of its neighbour on February 24. 

"Kyiv. A city under siege," presidential advisor Mykhailo Podolyak wrote on Twitter. He said the city was preparing a "ruthless defence".

Meanwhile, efforts continued to get help to Mariupol, which aid agencies say is facing a humanitarian catastrophe.

A humanitarian column headed there had to turn back again on Sunday, a city official said, after the Russians "did not stop firing."

A total of 2,187 residents have now died in days of relentless Russian bombardment, the city council said Sunday.

"The enemy is holding the city hostage by performing real acts of genocide," said Ukraine Defense Minister Oleksiy Reznikov.