KIEV — The embattled new government of Ukraine on Monday accused Russia of a major escalation in its effort to take control of the Crimea, saying the Russians had demanded that Ukrainian forces there surrender within hours or face armed assault.
Russia denied it had issued any ultimatum but was clearly moving to strengthen its grip on Crimea, brushing aside new admonitions from President Obama and European leaders of economic punishment and isolation. Investor jitters steered markets sharply down around the world.
The United States prepared to impose sanctions on high-level Russian officials involved in the military occupation. The Obama administration on Monday suspended military ties to Russia, including exercises, port visits, and planning meetings, just a day after calling off trade talks. If Moscow does not reverse course, officials said they will ban visas and freeze assets of select Russian officials in the chain of command as well as target state-run financial institutions.
Congressional leaders signaled that they would follow with sanctions of their own, plus quickly approve economic aid for the fragile pro-Western government in Ukraine.
At the United Nations, where the Security Council met for the third time in emergency session since Friday, the Ukraine ambassador, Yuriy Sergeyev, distributed a letter asserting that Russia had sent 16,000 troops into the Crimean peninsula since Feb. 24. The United States originally estimated that 6,000 Russian troops were dispatched there.
The troops, Sergeyev wrote, had moved to “seize, block, and control crucial governmental and military objects of Ukraine in Crimea.”
Although Crimea was relatively calm Monday, Russian forces tightened their grip on key military bases and other security facilities throughout the peninsula, including naval installations and outposts of the border police, and stepped up pressure on Ukrainian officials to declare their loyalty to pro-Russian authorities.
The Interfax-Ukrainian news agency quoted an unidentified Ukrainian Defense Ministry official as saying Russia’s Black Sea Fleet commander had set a Tuesday morning deadline for Ukrainian forces stationed in Crimea to lay down their weapons. Russia’s Interfax news agency said the Black Sea Fleet had no such plans.
The conflicting reports only further served to worsen tensions in the Ukraine crisis, which has grown drastically in scope within the past few weeks to a new confrontation between Russia and the West reminiscent of low points in the Cold War. In addition to roiling financial markets, the turmoil pounded the Russian ruble and drove up energy prices.
Obama, who spent much of the weekend working on the crisis, issued a new warning on the consequences to the Kremlin.
“What we are also indicating to the Russians is that if, in fact, they continue on the current trajectory that they’re on, that we are examining a whole series of steps — economic, diplomatic — that will isolate Russia and will have a negative impact on Russia’s economy and its status in the world,” he said.
EU foreign ministers, condemning Russia’s actions, called on Moscow to return its troops to their bases. EU heads of government will meet in an emergency summit meeting Thursday to discuss further steps. Radoslaw Sikorski, the Polish foreign minister, said: “The EU is saying that it will revise its relations with Russia if there is no deescalation.”
Visiting the new government in Kiev, Foreign Secretary William Hague of Britain urged Russia to pull back its forces in Crimea or face “significant costs,” echoing comments made by Obama and Secretary of State John Kerry, who was due here Tuesday.
Some divisions, however, among Europe’s leaders appear to be forming. German officials emphasized the need for diplomacy, while Dutch diplomats ruled out sanctions for now. A British government document photographed by a journalist said the government of Prime Minister David Cameron would not support trade sanctions or block Russian money from the British market.
Without European backing, US officials worry that economic sanctions may not carry enough bite to persuade President Vladimir V. Putin of Russia to reverse course. By itself, the United States is not even among Russia’s top 10 trading partners, with no more than $40 billion in exports and imports exchanged between the two each year. By contrast, Europe does about $340 billion in business with Russia, giving it far more potential clout, but also exposing it to far more potential risk.
“It’s particularly important for the United States to bring Europe along,” said Julianne Smith, a former national security aide to Vice President Joe Biden. “To the extent that the United States tries to put economic pressure on Russian industry, they won’t feel the impact as much as they would if we had Europe standing with us. That’s easier said than done.”
The Russian foreign minister, Sergei V. Lavrov, asserted that Russia was only protecting its interests and those of Russian citizens in Ukraine.
The use of Russian troops is necessary “until the normalization of the political situation” in Ukraine, Lavrov said at an opening of a monthlong session of the UN Human Rights Council in Geneva. “We are talking here about protection of our citizens and compatriots, about protection of the most fundamental of the human rights — the right to live, and nothing more.” But he did not specify what threats Russian citizens faced from Ukraine.
In a statement Monday night, Ukraine’s acting president, Oleksandr Turchynov, said that officers in Crimea had high morale and would defend themselves if necessary. “Nobody will ever give up Crimea,” he said.
Turchynov took no questions and did not mention reports of a Russian ultimatum, but said he had spoken earlier in the day with the commanders of army and marine bases on the Crimean peninsula and with the captains of Ukrainian naval ships blockaded in the Sevastopol harbor. He thanked the officers for resisting what he called “provocations” to fight by Russian soldiers.
But he described in detail a conversation with the captain and first mate of the Ternopol, a corvette in Ukraine’s navy, indicating commanders had been threatened with attack.
“A very dangerous situation emerged around the Ukrainian navy,” he said. “Russian servicemen have blockaded our naval ships in Sevastopol Bay, they have blocked the exits. Today, threats are coming, saying if the sailors do not surrender the ships and lay down their arms, they will attack our naval vessels.”
At the regional headquarters of the border police in Simferopol, the Crimean regional capital, a half-dozen men in plainclothes, some wearing face masks but carrying military radios, stood guard Monday outside the front door, where the glass had been smashed out during a siege of the building the day before.
At least three large Russian troop carriers were parked outside the building. Although most identifying markers had been removed, one of the trucks bore a black Russian military license plate carried by vehicles attached to the headquarters of the Black Sea Fleet in Sevastopol.