While the U.S. and Russia had already been in contact about security, the back-to-back attacks in the southern city of Volgograd have highlighted the terrorist threat Russia faces as it prepares to host the Winter Games in February. At least 31 people were killed in the separate explosions at a railway station and on a bus in Volgograd, which lies about 400 miles away from the site of the 2014 Winter Olympics.
The State Department on Monday urged Americans planning to attend the Olympics to remain alert at all times.
"Major events such as the Olympic games are an opportunity for thieves or for other folks who want to cause mischief," State Department spokeswoman Marie Harf said. "Threats have been made against the Olympic games and acts of terrorism, including bombings, continue to occur in Russia."
White House officials said President Barack Obama had been briefed on the attacks while on vacation in his home state of Hawaii. The White House has condemned the attacks and offered condolences to those injured and the families of those killed.
The upcoming Olympics have highlighted the complicated relationship between the U.S. and Russia. The two countries are necessary partners on an array on foreign policy matters, including Iranian nuclear negotiations and the effort to strip Syria of its chemical weapons stockpiles. Officials say counterterrorism cooperation between the U.S. and Russia has also increased following the April Boston Marathon bombing, which was believed to have been carried out by two brothers with ties to Russia's volatile Caucasus region. And Pentagon spokesman Col. Steve Warren made a point of stressing Monday that the military-to-military relationship between the two countries "is as good as it's ever been."
However, tensions mounted between the Obama and Russian President Vladimir Putin after Russia granted temporary asylum to Edward Snowden, the former U.S. government contractor who leaked secrets about American surveillance programs. Obama has also been publicly critical of a Russian law banning "gay propaganda."
In a clear message to Russia, the U.S. delegation to the Olympics includes several openly gay athletes, including tennis player Billie Jean King and figure skater Brian Boitano. And for the first time since 2000, the American delegation to the Olympics will not include a president, vice president or first lady.
Associated Press writers Sagar Meghani and Deb Riechmann contributed to this report from Washington
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