People visiting Sochi should "watch their backs," California Sen. Dianne Feinstein told CNN's Jake Tapper on Thursday. According to ABC News, the Department of Homeland Security has announced new restrictions on carrying liquids and gels on planes between the United States and Russia, apparently due to increased security concerns surrounding the Olympics. No toothpaste, no face wash.

The Wire reported on government warnings about possible attacks using explosives smuggled in toothpaste tubes on planes. On Thursday, the TSA acted on that speculation, banning "liquids, gels, aerosols, powders" on flights between Russia and the United States — though those items can still be carried in checked bags.

Appearing on Tapper's The Lead, Feinstein expanded on the government's security concerns. "There's a blanket of security," Feinstein said, but people attending the Games should "watch their backs," and avoid crowds, if they can. "The threat stream is credible," she said. "I think it's real."

At the end of last month, the Office of the Director of National Intelligence released its 2014 Worldwide Threat Assessment, which included a warning about Sochi. The office didn't seem panicked, saying, "we have seen an increase in threat reporting just prior to the Olympics, which is not unusual for a major international event, and have offered assistance to the Russian Government." But Director James Clapper, under strong political pressure in the wake of the leaks from Edward Snowden, expanded on the broader threat in testimony before the Senate Select Intelligence Committee, which Feinstein chairs.

"Looking back over my more than half a century in intelligence," Clapper said, "I have not experienced a time when we have been beset by more crises and threats around the globe." As The Guardian's Michael Cohen notes, though, he used similar language in 2013 and 2012. "We are a remarkably safe and secure nation," Cohen wrote, "protected by two oceans, an enormous and highly effective military and dozens upon dozens of like-minded allies and friends around the world." His point, in brief: "America doesn't face a single truly serious security threat." Clapper's job is to assess and address any risk to the country or its citizens. But there's no question heightened security concerns relieve some of the pressure he and his agency are under from members of Congress and the public.

Which is not to say that no risk exists for tourists and athletes in Sochi. The escalation by the TSA is only the most recent in an increasing sense of concern about security at the Olympics. At the Daily Beast, Jacob Siegel reports that "it’s more than likely" militants entered the Olympics secure zone as part of the construction workforce before it was sealed off. Siegel notes the pair of bombings in the region last December as examples of the sort of attacks that might be undertaken. Interviewed by Siegel, the director of security at the 1996 Games said, "I would be afraid to use public transportation in Sochi during the games."

All sides, of course, hope that nothing happens. But this is the side of the NSA and the DNI that Clapper and Feinstein want the world to see: in action, engaged, and ever vigilant.