It came as US President Joe Biden told Russian leader Vladimir Putin to stand down troops on its border with Ukraine during a fiery phone call between the leaders. Mr Biden “voiced concerns over the sudden Russian military build-up in occupied Crimea and on Ukraine’s borders,” the White House said. He called for a peace summit but warned “the United States will act firmly in defence of its national interests in response to Russia’s actions,” US officials said.
The crisis is Mr Biden’s first major foreign policy test since taking office. He spoke of his “unwavering commitment to Ukraine’s sovereignty and territorial integrity” and proposed a summit in the coming months, officials said. There was no indication of Mr Putin’s response.
Moscow later said the call took place at Washington’s request.
Hours earlier, Sergei Ryabkov, Russia’s deputy foreign minister, had warned the US to keep its warships out of the Black Sea.
He said the decision to deploy two destroyers – the USS Donald Cook and USS Roosevelt – to the area is “a provocation” designed “to test our nerves”. He called America “an adversary”, ramping up a war of words between the superpowers.
Mr Ryabkov added: “There is absolutely nothing for American ships to be doing near our shores, this is purely a provocative action.
“They are testing our strength, playing on our nerves. They will not succeed. We warn the US that it will be better for them to stay far away from Crimea and our Black Sea coast. It will be for their own good.”
The two US warships are thought to be en route to the Black Sea from a base in Spain and due to arrive today and tomorrow.
It comes as the RAF deploys Typhoon fighter jets to Eastern Europe with border tensions between Ukraine and Russia on high alert. Six supersonic aircraft will fly to Romania to police the skies around the Black Sea.
The Typhoons will be supported by troops from the RAF’s No.1 Expeditionary Logistics Squadron and No.2 Mechanical Transport Squadron deploying this week.
The deployment of the jets is part of an annual Nato air policing mission, Operation Biloxi.
Up to 100 British infantry troops are also expected to be sent to Ukraine to take part in joint exercises this summer.
Ukrainian president Volodymyr Zelensky requested talks with Mr Putin three weeks ago following the deaths of four of his troops in a mortar attack. Of the silence his spokesman said: “We very much hope that this is not a refusal of dialogue.”
Ukraine claims Russia has deployed 41,000 troops to the border in eastern Ukraine and 42,000 to Crimea with those numbers multiplying all the time.
Moscow maintains the movement is part of an exercise but Russian state TV Moscow said it was “one step away from war”.
Tensions between Russia and Ukraine, which achieved independence in 1991 after the Soviet Union was dissolved, have been on a precipice since 2014.
Since Russia annexed eastern Ukraine more than 14,000 people have been killed in sporadic clashes on the front line.
Analysis by Col Richard Kemp
It is not clear whether President Putin’s mobilisation towards Ukraine was motivated by a desire to warn President Biden against sanctions, to frighten the EU from backing them, rally flagging support at home in the face of dire economic conditions, or all three.
Whatever his rationale, it could lead to a conflict he didn’t intend.
Biden cannot afford to show anything other than strength towards Russia at this stage of his leadership, especially given his frequent suggestions of Trump-Russia collusion.
US sanctions that Putin hoped to deter look like they’re on the way. The EU – usually to be relied on to vacillate and buckle in the face of pressure – has shown uncharacteristic strength in its support for the Ukraine under Russian threats, backed by NATO.
Equally, Ukrainian President Volodymyr Zelenskiy has stood more firmly than Putin expected.
One thing is clear: having decided to threaten Ukraine, Putin cannot show the weakness that would be exploited by his rivals were he to back down. He has to do something aggressive rather than just pretend he was conducting military manoeuvres.
That would be immensely damaging at home. He will not want to order a major invasion which would have much wider and potentially catastrophic consequences for Russia.
There are various tactical factors, including weather and a current lack of some necessary military assets on the ground.
More likely would be infiltration by deniable forces, such as the “little green men” that took over the Crimea in 2014 or peacekeeping troops to protect the Russian speakers in Donbas that never get around to leaving.