Russian forces have taken over the Ukrainian minesweeper Cherkasy, the last military ship controlled by Ukraine in Crimea, in an operation in which they used stun grenades and fired in the air, Ukrainian naval sources said on Wednesday.
During the operation there was an explosion on board the ship, which was in an inlet called Donuslav Lake, which apparently damaged its engines.
"The Cherkasy has been taken over and as the engine was damaged during the raid it had to be towed away by a tug boat to the anchorage," Ukrainian navy spokesman Vladislav Seleznyov said.
There were no injuries and the crew remained on board until the morning when they went ashore.
During the take-over, which began on Tuesday evening, the minesweeper used water cannon in an effort to repel the Russian forces who had approached the Cherkasy in speedboats. "Russians threw stun grenades and fired small arms, apparently in the air," a navy source said.
Russian forces have used similar tactics to seize ships and military bases from the last remaining Ukrainian troops in Crimea in recent days as part of Russia's largely bloodless annexation of the region.
Kiev, which calls Russia's annexation of Crimea illegal, ordered its remaining forces to withdraw for their own safety on Monday, but not all troops have yet left the Black Sea peninsula and some ships have been prevented from leaving.
On Monday, Cherkasy attempted without success to break to the open sea through a blockade at the entrance to the inlet. The Russian navy blocked the route earlier this month by scuttling three hulks in the channel.
RUSSIAN TROOP BUILDUP
US and European security agencies estimate Russia has deployed military and militia units totalling more than 30,000 people along its border with eastern Ukraine, according to US and European sources familiar with official reporting.
The current estimates represent what officials on both sides of the Atlantic describe as a continuing influx of Russian forces along Ukraine's frontier, the sources said.
The 30,000 figure represents a significant increase from a figure of 20,000 Russian troops along the border that was widely reported in US and European media last week.
But US and European security sources noted that these estimates are imprecise. Some estimates put current troop levels as high as 35,000 while others still suggest a level of 25,000, the sources said.
However, the sources said that US and European government experts believe that there has been, and continues to be, a steady and noticeable buildup in the total number of Russian forces along the Ukrainian border, though some military units have rotated in or out of the area.
US and European security sources said that the Russian force deployed along the Ukraine border includes regular military including infantry and armoured units and some air support.
Also deployed are militia or special forces units comprised of Russian fighters, wearing uniforms lacking insignia or other identifying markings, similar to the first Russian forces to move into Crimea during Russia's recent military takeover there.
US officials said that what Russian President Vladimir Putin actually plans to do with his forces deployed on the Ukraine border is unknown. Some officials say intelligence information available to policymakers regarding what Putin is thinking, and what he is saying to his advisors and military commanders, is fragmentary to non-existent.
But the portents are potentially ominous. "No one's ruling out the possibility of additional Russian military aggression," one US official said.
US President Barack Obama was non-committal when asked about the 30,000 Russian troops estimate at a news conference in The Hague on Tuesday.
"With respect to the Russian troops that are along the border of Ukraine at the moment, right now they are on Russian soil. And if they stay on Russian soil, we oppose what appears to be an effort of intimidation, but Russia has a right, legally, to have its troops on its own soil.
"I don't think it's a done deal. And I think that Russia's still making a series of calculations," Obama said.