Joe Biden says risk of Russian invasion of Ukraine ‘very high’

Joe Biden has said he believes Russia is on the brink of invading Ukraine, as he joined Nato allies in warning that shelling in the disputed east of the country may be an attempt to set up the pretext for an incursion.

Claims of attacks by Russian-backed separatists at several locations in Ukraine's Donbas region, including at a kindergarten and a school, were said to bear the hallmarks of an attempt to incite conflict.

The US president, speaking shortly after the expulsion of his country's deputy ambassador to Moscow, said his administration had "reason to believe" that Russia was "engaged in a false-flag operation to have an excuse to go in".

The president made his comments as Russia handed over its long-awaited response to American and Nato proposals about European security.

The Kremlin said in its 10-page letter that the US had not taken its concerns seriously about Ukraine's potential to join Nato and that Russia would need to take unspecified "measures of a military-technical nature".

Biden ordered his secretary of state, Antony Blinken, to change his travel plans at the last minute in order to speak at a United Nations security council meeting on Ukraine.

Russia continues to deny that it has any intention of invading Ukraine but Blinken told those assembled that they found themselves in a "moment of peril for the lives and safety of millions of people".