Further violence in Ukraine marks a dangerous escalation, but there is no way of verifying the latest reports of a Russian invasion, a top UN official told the Security Council today.
In an emergency session on the growing crisis, members expressed outrage, with US ambassador Samantha Power saying Russia "has manipulated. It has obfuscated. It has outright lied."
The emergency Security Council meeting came hours after a top Ukrainian official said two columns of Russian tanks and military vehicles fired missiles from Russia at a Ukraine border post, then rolled into the country. That opened a new front in the war in eastern Ukraine between pro-Russia separatists and the new government of President Petro Poroshenko.
Statements from Nato, Mr Poroshenko, the separatists, the United States and the president of the Security Council left no doubt that Russia had invaded Ukraine.
A top Nato official said at least 1,000 Russian troops have entered Ukraine with sophisticated equipment and have been in direct "contact" with Ukrainian soldiers, resulting in casualties.
The new south-eastern front raised fears that the separatists are seeking to create a land link between Russia and Crimea, which Russia annexed in March.
UN undersecretary-general of political affairs Jeffrey Feltman opened the meeting, telling council members the latest developments mark a "dangerous escalation in the conflict".
Ms Power reminded the council that the meeting was "the 24th session to try to rein in Russia's aggressive acts in the Ukraine".
"Every single one has sent a straightforward, unified message: 'Russia, stop this conflict'. Russia is not listening," she said, adding that Russia's force along the border is the largest it has been since it started deploying in late May.
"We will continue working with G7 partners to ratchet up consequences on Russia," Ms Power said.
France also threatened that sanctions will be increased if the escalation continues.
Prior to the meeting, Russian ambassador to the UN Vitaly Churkin told reporters "You're at a loss", offering no further comment.
UK ambassador Mark Lyall Grant told reporters: "Russia will be asked to explain why Russia has its troops inside Ukraine. It's very clear that Russian regular troops are now in Ukraine."
Lithuania's UN ambassador, Raimonda Murmokaite, who requested the emergency meeting, tweeted prior to its start: "An invasion is an invasion is an invasion."