Russia has agreed to a meeting with representatives from NATO on Wednesday to discuss the Ukraine crisis as Kyiv’s new leadership has announced the start of direct talks with Moscow to ease the last days’ tension, particularly at the pro-Russian region of Crimea.

Speaking at the Ukrainian capital, after a meeting with the new Prime-Minister and President, U.S. Secretary of State John Kerry on Tuesday condemned Russia’s “act of aggression” in Ukraine and said Moscow, which has taken control of the Crimea region, was looking for a pretext to invade more of the country. Kerry threatened Russia with “isolation” if the country “don’t de-escalates the situation”. The United States has begun spelling out its response to Russia’s incursion, announcing a suspension of all military engagements with Russia, including military exercises and port visits, and freezing trade and investment talks with Moscow.

Hours earlier, President Vladimir Putin said that Russia saw no need to use military force in the Crimea region of Ukraine for now, in remarks apparently intended to ease East-West tension over fears of war in the former Soviet republic.

The use of force by Russia in Ukraine would be a choice of last resort, Putin said, and sanctions being considered against Moscow by the West would be counter-productive.

Putin told a news conference at his state residence outside Moscow there had been an “unconstitutional coup” in Ukraine and ousted leader Viktor Yanukovich, an ally of Russia, was still the legitimate leader of the country despite giving up all power.

Putin ordered troops involved in a military exercise in western Russia back to base on Tuesday in an announcement that appeared intended to ease East-West tension over fears of war in Ukraine.