Ralph Lauren/AP Photo

American athletes are being warned not to wear their Team USA Olympic gear outside of official venues in Sochi. And when they're competing, American security agents will be keeping a watchful eye, a senior administration official said today.

The clothes warning is a "common sense" measure and, like in games past, agents with the State Department's Diplomatic Security arm will accompany American athletes to all their events, said the official, who spoke on background with reporters on a conference call.

The agents will accompany athletes to "make sure we've got eyes on the teams and eyes on the events," the official said, adding that they will accompany teams "to all the venues" and "they'll be onsite at all times."

Diplomatic Security agents have accompanied U.S. teams to events at past Olympic games, the official noted.

"That's typically what we do. That's our role out there. That's why we ask for the accreditation process," the official said, referring to visa requests for Russia to accredit additional American personnel to enter the country and provide security in Sochi.

A Diplomatic Security spokesperson declined to say whether the agents would be armed or provide specifics about plans for how to deploy them.

The U.S. Olympic Committee has cautioned athletes not to wear their USA gear outside official Sochi venues, as the Wall Street Journal first reported today.

"This was based on discussions with the State Department," agency spokeswoman Marie Harf told reporters at today's daily press briefing.

"Just being careful about where you wear U.S. logos or things like that - this isn't unique to Russia, to be clear. We generally give this kind of guidance around big international events, particularly if there is some kind of threat like we've seen here," Harf said.

The senior administration official supported the USOC's warning. "We're not sure if they're actually true or not, or how serious they are, but given those threats [reported in recent weeks], I think it's reasonable," the official said, citing experts who have said "soft targets" outside official Olympic venues are more vulnerable to terrorist attacks. The advice was given to athletes "by the security coordinator for the U.S. Olympic team," the senior administration official said.

The FBI, meanwhile, will have representatives in Sochi, a senior administration official told reporters, and the U.S. will operate a "joint operation center" for security at the games.

Security concerns have been raised by Russian officials' reported hunt for a female, so-called "black widow" suicide-bomb plotter in Sochi, and by threats released by terrorist groups. U.S. officials said the Pentagon will keep two ships on standby in the Black Sea for, among other purposes, possible evacuation of Americans from Sochi.

The U.S. expects as many as 10,000 Americans to visit the games, along with 230 athletes and 270 coaches and support staff, an administration official said today.