The US and Russia engaged in a public diplomatic brawl on Monday at the UN Security Council over the Ukraine crisis, with the Americans accusing the Russians of endangering peace by massing troops on Ukraine’s borders and Kremlin diplomats dismissing what they called farcical theatrics and fear-mongering.

Almost immediately after the meeting of the 15-nation council convened, the Russians objected to even holding it. Ambassador Vasily Nebenzia of Russia accused the Americans of fomenting “unfounded accusations that we have refuted” and said the meeting would not help “bring this council together”.

He said no Russian troops were in Ukraine, questioning the basic premise of a meeting he described as “megaphone diplomacy”.

The American ambassador, Linda Thomas-Greenfield, countered that many private diplomatic meetings had been held about Russia’s military build-up and it was “now time to have a meeting in public”. She asked other members how they would feel “if you had 100,000 troops sitting on your border”.

The council voted to proceed with the meeting, with only Russia and China objecting.

“The situation we are facing in Europe is urgent and dangerous,” Thomas-Greenfield said in her opening remarks. “Russia’s actions strike at the very heart of the UN charter.”

The Russian military buildup, she said, reflected “an escalation in a pattern of aggression that we’ve seen from Russia again and again”, and that if the Russians invaded Ukraine, “none of us will be able to say we didn’t see it coming”.

The meeting of the council, requested by the US last week, represents the highest-profile arena for the two powers to sway world opinion over Ukraine. The tensions surrounding the former Soviet republic have brought US-Russian relations to their lowest point since the Cold War.

As one of the five permanent members of the council — along with Britain, China, France and the US — Russia has the power to veto any decision by the majority. But veto power cannot be used to block a meeting.

Russian diplomats have ridiculed the meeting as part of a manufactured contretemps over what they call unjustified western fears, instigated by the US, that President Vladimir V. Putin of Russia is preparing to invade Ukraine.

Putin, who has not spoken publicly about Ukraine since December, maintained his silence.

His spokesman, Dmitri S. Peskov, told reporters on Monday that Putin would state his views on the situation “as soon as he determines it to be necessary”.

“I can’t give you an exact date,” Peskov said. Russian officials continued to maintain they were not at fault for the rising tensions, insisting that the United States was fabricating the threat of a Russian invasion of Ukraine.

(New York Times News Service