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Russian forces armed with machine guns and stun grenades stormed one of the few remaining Ukrainian military bases in Crimea Monday, and took two wounded servicemen captive. Ukraine's new government ordered its troops and their families to withdraw from Crimea after the latest of several base seizures since Russia formally annexed the territory last week.

Ukraine's Defense Ministry says as many as 80 of its troops were detained at the naval base in the Crimean port of Feodosia. The Russian military has been systematically taking over Ukrainian ships and military installations in Crimea since Friday’s annexation from Ukraine.

Thousands of Ukrainian troops have been besieged on bases in Crimea in recent days, offering no armed resistance, but refusing to surrender.

A Ukrainian Army officer, 1st Lt. Anatoly Mozgovoy, told Reuters by phone from inside the Feodosia compound that the Russians had fired shots at unarmed Ukrainian soldiers. ``The interior of the compound is full of Russian troops,'' Mozgovoy said.

In a symbolic gesture, Ukrainian flags were taken down inside the base. The Russian Defense Ministry said the Russian flag was now flying above 189 military facilities in Crimea.

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Ukraine's acting president, Oleksandr Turchnynov, says the Defense Ministry has been instructed to redeploy Ukrainian servicemen from the Black Sea peninsula to Ukraine's mainland. Speaking to leading lawmakers in the Ukrainian capital, Kiev, Turchnynov said Ukrainian troops would be evacuated with their families amid unspecified threats from what he termed occupying Russian forces, Reuters reported.

“Despite the huge losses, Ukrainian forces in Crimea have fulfilled their duty. They provided the ability and time for the Ukrainian armed forces to be able to ensure defensive preparations and for partial mobilization to be organized.'' Turchinov said.

With the storming of at least three military facilities over the past three days alone, it wasn't clear how many Ukrainian troops remained on the peninsula. Over the weekend, Russian forces stormed the Belbek air force base near Sevastopol and detained the commander. Two days after the Belbek storming, the commander of the airbase, Colonel Yuliy Mamchur, remains a captive. His aides believe he is being held in the Russian Black Sea Fleet's home town of Sevastopol.

Ukrainian forces also abandoned a naval base after attacks by pro-Russian protesters, and were forced to surrender two flagship vessels to Russian forces over recent days.

Russia completed its annexation of Crimea last week, after its troops took control over the Ukrainian region following the ouster of a Kremlin-friendly government in Kiev.

Moscow says its absorption of Crimea has been rendered legitimate by a referendum held earlier this month in which the bulk of voters in the peninsula approved the move, but the process has come under sustained criticism from the international community.

The situation in Ukraine is set to dominate President Obama's agenda as he begins a week of international travel in the Netherlands to attend a nuclear security summit. The two-day summit has been expected to be the focus of Obama's visit, but the event will now be overshadowed by hurriedly scheduled talks on Ukraine among the Group of Seven industrialized economies -- the U.S., Britain, Canada, France, Germany, Italy and Japan.

Russian Foreign Minister Sergei Lavrov is expected to meet his Ukrainian counterpart Andriy Deshchytsya during the nuclear security summit now under way in the Hague, a Russian diplomatic source said Monday. The Ukrainian delegation had asked for the meeting, according to the source cited by Russian news agencies RIA and Interfax.

Russia said Monday that it was barring 13 Canadian lawmakers, officials, and public figures from the country in retaliation for sanctions imposed by Canada over the annexation of Crimea.Canadians prohibited from entering Russia include aides to Prime Minister Stephen Harper, the head of the Ukrainian Canadian Congress, and some parliament members, the Russian Foreign Ministry said in a statement reported by Reuters.

As political tension rises, British Prime Minister David Cameron announced Monday that the G8 group of industrialized nations will not meet in Russia this year, ``We should be clear there's not going to be a G8 summit this year in Russia. That's absolutely clear,'' Cameron told reporters on a visit to a nuclear security summit in The Hague.

Also Monday, Russia's SMP Bank said Monday that depositors withdrew about 9 billion rubles ($249 million) since U.S. sanctions were announced last week..

Washington imposed sanctions Thursday against 20 Russians in President Vladimir Putin’s inner circle as punishment for annexing Crimea from Ukraine. Boris Rotenberg and his older brother Arkady -- co-owners of SMP Bank -- were among those to have their visas banned and assets frozen.

SMP CEO Dmitry Kalantyrsky told a news conference that an estimated 4 billion rubles ($110 million) had been withdrawn by individuals and 5 billion ($138 million) by organizations.

The Associated Press and Reuters contributed to this report.