CNN — Several members of Congress said they're concerned about security surrounding next month's Winter Olympics in Sochi, Russia.
The concerns stem from a pair of December bombings in the city of Volgograd that killed more than 30 people.
On Sunday, a video of two young men claiming responsibility for the attacks emerged on a well-known online forum.
The men promise a, "present" for visitors to the winter games.
Russia has beefed up security surrounding the event and President Vladimir Putin has pledged that visitors will be kept safe.