SEVASTOPOL, Ukraine -- The embattled government in Kiev said Monday night that Russian forces had dramatically escalated the standoff between the two nations by giving Ukraine's army and navy in Crimea a blunt 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 berthed 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 autonomous Crimean Peninsula, it was clear that Ukrainian forces believed that they faced an imminent threat, even though no shot had been fired.
A Ukrainian Defense Ministry official alleged that Russia's Black Sea Fleet commander had set a deadline of 5 a.m. today -- 10 p.m. Monday Eastern time -- for Ukrainian forces to capitulate, according to the Interfax-Ukrainian news agency.
The stepped-up Russian troop movements came 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 actions Monday triggered a cascade of condemnation from European and U.S. officials, who vowed that Russia would face consequences if it did not pull back its soldiers.
Here in the deep-water harbor at 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. A nearby Ukrainian naval station flew a Russian flag.
As the anxious wives of officers on the Ukrainian ship watched from shore, its crew rushed about in what appeared to be an attempt to repel boarders. The sailors -- who carried sidearms and military 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 arms and leave the ships, according to the UNIAN news agency, quoting a Ukrainian military source.
Ukrainian officials expressed fears 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, he said: "We call on you to come to your senses. We call on you to stop."
Ukraine's acting president, Oleksandr Turchinov, said Monday that 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.
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 news media reported that a representative of 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. By nightfall, the Ukrainian aviators were still on their air base.
Some military experts said that, despite appearances, they doubted that Russia was eager for a fight that might carry a steep price. Even in eastern Ukraine, where Russian is the predominant language, an incursion by Moscow could be a force to unify the divided country, said Dimitry Gorenburg, a senior research scientist at the Center for Naval Analyses in Alexandria, Va.