The recent ban on toothpaste on Russia-bound aircraft grew out of the discovery of a larger, ongoing plot by terrorists to explode a bomb on a plane during the Olympics, U.S. law enforcement and intelligence sources told ABC News today.
"That is an ongoing concern right now, the effort to put a bomb on an airplane right now in or around Sochi… that Russian intelligence agents are looking very closely at," said Seth Jones, a counter-terrorism expert at the RAND Corporation.
The intelligence on the plot also indicated terrorists could use tiny detonators taken from weapons, such as rocket-propelled grenade launchers, being used by Islamist fighters in Syria, the sources said.
The Department of Homeland Security Wednesday sent a notice to U.S.- and foreign-based airlines, alerting them that no liquids or gels would be allowed in the carry-on luggage for travelers heading to Russia, as first reported by ABC News. Today the State Department issued an updated travel alert for those going to Russia, explaining Russia announced a similar travel restriction last month "in response to potential security threats against commercial aircraft."
The new threat, however, is "specific and credible," according to House Homeland Security Chairman Michael McCaul and other top U.S. lawmakers involved in intelligence and security matters.
Security in Sochi has been high for months due to the threat posed to the Games by Islamic militants in the region.
Sochi lies on the Black Sea, just 300 miles away from the heartland of an Islamic militancy in the North Caucasus. Doku Umarov, the leader of the insurgents known to some as Russia's Osama bin Laden, told his followers last summer they should do what they can to disrupt the Games, which he called a "satanic dance" on the bones of their ancestors.
In the past three months, Russia has suffered three suicide bombings in southern cities attributed to the militants. Today's State Department alert repeated advice to its citizens traveling to Sochi to be "vigilant and exercise good judgment" during the Games because of the terror threat.
The head of the Department of Homeland Security said today the department is "continually evaluating" whether additional travel restrictions are necessary.
"DHS monitors world events in real time and takes action, when necessary, to confront and respond to threats," DHS Secretary Jeh Johnson said at an event in Washington, D.C. "In support of Russian authorities, we are keeping a close eye on the Sochi Olympics. Within the last 48 hours, we have, out of an abundance of caution, issued advisories to air carriers and others based on what we've learned, adjusted TSA [Transportation Security Administration] security measures, and are continually evaluating whether more is necessary."
On the other side of the globe in America, Johnson said that though DHS is keeping an eye out for any further need to boost security measures, he's hoping things stay quiet.
"In the homeland security world, no news is good news, and no news is often the result of the hard work, vigilance, and dedication of people within our government who prevent bad things you never hear about," he said.