President Vladimir Putin yesterday accused the United States of raising the risk of nuclear war by threatening to spurn a key arms control treaty and refusing to hold talks about another pact that expires soon.
The United States has threatened to pull out of the 1987 Intermediate-range Nuclear Forces Treaty (INF) which bans Moscow and Washington from stationing short and intermediate-range, land-based missiles in Europe.
Putin said the move, if it happened, would have unpredictable consequences.
"We are essentially witnessing the breakdown of the international arms control order and (the start of) an arms race," Putin told his annual news conference with hundreds of reporters.
"It's very hard to imagine how the situation will develop (if the US quits the INF treaty). If these missiles appear in Europe what should we do? Of course, we'll have to ensure our own security."
Another US-Russia treaty, the New START pact, which limits the number of deployed strategic nuclear warheads each side can have, expires in 2021. Putin said he was worried that Washington didn't appear to be interested in discussing its future.
The Russian leader, who said Moscow had developed nuclear weapons which he believed gave it an edge over other countries, warned the threat of a nuclear conflict was growing as a result of the US moves. He also cited the dangerous tendency of lowering the threshold for using nuclear weapons and the idea of using ballistic missiles with conventional warheads.
"If, God forbid, something like that were to happen, it would lead to the end of all civilisation and maybe also the planet," said Putin.
"I hope that humankind has enough common sense and sense of self-preservation not to take things to such extremes."
Putin said that he largely agreed with Trump that Islamic State had been defeated, but added that he was sceptical whether the United States would withdraw fully from Syria. Putin however said Moscow had not noted any signs of a US withdrawal, and that the US had many times said it was leaving Afghanistan, but still retained a presence there.
Answering a question, Putin said that he did not know whether he would meet Trump soon, but that it was important for Moscow and Washington to normalise relations.
On Ukraine, Putin said that he was willing to respect a Russian-Ukrainian accord governing the joint use of the Azov Sea and that Moscow wanted to normalise the situation around the waters.
On spy cases in Britain and other places, the Russian president dismissed the incidents as an attempt by western powers to undermine the country's international standing.
The annual event, Putin's 14th of its kind, is used by the Russian leader to burnish his leadership credentials and send messages to foreign allies and foes.
Putin, 66, has been in power, either as president or prime minister, since 1999.