(CNN) -- A video surfaces threatening the Winter Olympics. Russia's President vows the Games will be safe. Some U.S. lawmakers warn that they won't be. One thing was clear as debate over the situation surged on Sunday: security is a top concern, less than three weeks away from the competition. "It's a very serious fear," Sen. Angus King, I-Maine, told CNN's State of the Union Sunday. Russian President Vladimir Putin acknowledged that the Games, like any high-profile event, could be a target for terrorists. But, he said, Russia has a "perfect understanding" of the threat and how to stop it.
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NEW: U.S. lawmakers say they're concerned about security at the Olympics
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A video on a well-known Jihadi website threatens the Winter Olympic Games
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Russia will do its utmost to keep Sochi visitors safe, says President Vladimir Putin
When it won the bid in 2007, @placeholder said the Winter Games would cost $12 billion, but the government's website now cites the total cost as 1.5 trillion rubles ($45 billion.)