Winter Olympics 2014: US athletes warned not to wear team gear outside Sochi Olympic venues The warning for American athletes not to advertise their nationality due to security concerns came in a memo from the committee, which prepared it with the advice of the State Department, officials said, confirming a report in the Wall Street Journal. State Department spokesman Marie Harf said "the US Olympic Committee, I think, had discussed with its athletes, as part of how to sort of stay safe and things to look out for as part of the Games, this issue about ... just being careful about where you wear US logos or things like that." The White House has signaled concern over Russia's security preparations for next month's Winter Games in the Black Sea resort of Sochi, with officials privately complaining about Moscow's refusal to share intelligence on terror threats. The United States has said repeatedly it is ready to provide help to Russia to ensure security for the event, a question which came up in a telephone conversation on Tuesday between President Barack Obama and Russian President Vladimir Putin. The Pentagon has announced it is deploying two warships to the Black Sea as a "precaution" in case of a terror attack. Islamist insurgents based in North Caucasus republics such as Dagestan, who are seeking their own independent state, have vowed to disrupt the Games in a bid to undercut Putin. In a recent video threat posted on a prominent North Caucasus Islamist website, two men sitting in front of a jihadist flag warn of planned attacks at the February 7-23 event.