SEVASTOPOL, Ukraine — Government officials in Kiev said Monday night that Russian forces escalated the standoff between the two nations by giving Ukraine’s army and navy in Crimea an ultimatum: pledge allegiance to the region’s new pro-Russia leadership by morning or be forced by Russia to submit.
A spokesman for the Russian Black Sea Fleet, which is based in the Crimean port of Sevastopol, denied that a threat had been made and the Russian Defense Ministry called the accusation “utter nonsense.”
But as Russian troops and warships surrounded Ukrainian security installations throughout the Crimean peninsula, it was clear that Ukrainian forces believed they faced an imminent threat even though no shot had been fired.
Russian troop movements accelerated two days after the Russian parliament approved the use of force to protect the country’s citizens and military sites in Crimea, a region with deep ties to Russia.
The developments on Monday triggered condemnation from European and American officials, who vowed that Russia would face consequences if it did not pull back.
President Obama said that Moscow was “on the wrong side of history” and threatened “a whole series of steps — economics, diplomatic” to isolate Russia.
In Sevastopol, a Ukrainian naval command ship was confronted Monday evening by four tugboats flying Russian colors and boxed in by a Russian minesweeper. Other Russian warships appeared at the mouth of the harbor to block an escape to the sea.
The Ukrainian ship’s crew rushed about in what appeared to be an attempt to repel boarders. The sailors — who carried sidearms and assault rifles — fixed mattresses to the railings, uncoiled fire hoses, and brought firefighting equipment on deck.
On Monday night, the Russian Black Sea Fleet ordered the crew members to lay down their weapons and leave the ships, according to the UNIAN news agency, quoting a Ukrainian military source.
Ukrainian officials expressed concerns that the tensions could lead to violence overnight, which could give Russia reason to justify military action.
“Provocations with killing of three to four Russian soldiers are planned on the territory of Crimea tonight,” said Deputy Interior Minister Mykola Velichkovych, the ministry’s press service reported.
Speaking to the Russians, Mr. Velichkovych said: “We call on you to come to your senses. We call on you to stop.”
Ukraine’s acting president, Oleksandr Turchinov, said he had been in communication with Ukraine’s military commanders in Crimea, and they assured him that they would not yield to the Russians, according to the UNN news agency of Ukraine.
Western diplomats pressed for Russia to pull back.
In an interview with the BBC, British Foreign Secretary William Hague said from Kiev that the Russian intervention in Crimea has produced “a very tense and dangerous situation” that amounted to Europe’s “biggest crisis” so far in the 21st century.
“The world cannot just allow this to happen,” said Mr. Hague, whose American counterpart, Secretary of State John Kerry, was scheduled to arrive in Kiev today.
At the United Nations, the Security Council held its third emergency meeting in four days amid fears that the Kremlin might carry out more land grabs in eastern Ukraine.
Russian U.N. Ambassador Vitaly Churkin defended his government’s actions as “fully appropriate and legitimate” to defend the human rights of the Russian-speaking minority in Ukraine, which he claimed is under threat of oppression after violent protests swept in a new government.
He told the council he was authorized to read a statement from fugitive President Viktor Yanukovych requesting Russian President Vladimir Putin to use his forces to restore peace.
Mr. Yanukovych fled the former Soviet republic to Russia after his ouster.
U.S. Ambassador Samantha Power dismissed Moscow’s contention that it intervened militarily in Crimea to protect the human rights of Russian civilians there as “baseless,” insisting there is no evidence of any threats against ethnic Russians in Ukraine.
Ukraine’s U.N. Ambassador Yuriy Sergeyev pleaded for help and sent a letter to all 193 U.N. member states detailing Russia’s takeover of crucial government and military facilities in Crimea.
In Washington, State Department spokesman Jen Psaki said the Obama Administration is “highly likely” to impose additional economic and political sanctions on Russia unless it sends its troops in the Crimea back to Russian bases.
“We are not just considering” additional steps, she said. “It is likely we will put [sanctions] in place.”
Meanwhile, Poland called for an urgent meeting of NATO, saying it feels threatened by Moscow’s moves.
The Polish request for a meeting of NATO’s North Atlantic Council came under the same provision that led the alliance early last year to deploy Patriot missile batteries in Turkey for protection against Syria.
The comments appeared to make little impact on Russia.
In Geneva, Russian Foreign Minister Sergei Lavrov justified the Russian troop deployment as necessary to protect Russians living in Crimea “until the normalization of the political situation” in Ukraine.
Russian forces, already in control of much of Crimea, took possession of a ferry terminal in Kerch, in the eastern part of the peninsula just across a strait from Russian territory, according to reports from the area.
The terminal serves as a departure point for many ships heading to Russia and could be used to send even more Russian troops into Crimea.
Ukrainian media reported that Russia’s Black Sea Fleet also called on members of Ukrainian Aviation Brigade at an air base in Belbek to denounce Ukrainian government authority and swear allegiance to the new Crimean government.
In Kiev, interim Prime Minister Arseniy Yatsenyuk urged the West to provide political and economic support as the Kiev stock market dropped a record 12 percent and the Ukrainian currency, the hryvnia, fell to new lows against the dollar and euro.
The crisis also caused the Moscow market to fall 10 percent and the Russian ruble to dive.
Mr. Yatsenyuk emphasized that Crimea remained part of Ukraine, but he conceded that there were “for today, no military options on the table.”
Obama Administration officials said Russia now has 6,000 troops in Crimea.
Ukraine’s ambassador to United Nations said Monday that 16,000 additional Russian troops had been deployed to Crimea in last six days. Military experts estimate the size of the Ukrainian military in Crimea is about 30,000, but many of those are support staff.