Airlines have been warned about the possibility of a new shoe bomb threat by the Department of Homeland Security, it was revealed on Wednesday.

According to USA Today, the warning specifies that incoming flights from outside the country should be particularly monitored.

A DHS official said, "Out of an abundance of caution, DHS regularly shares relevant information with domestic and international partners about relevant threat information."

It is said that this new warning does not relate to the one that was sent out at the beginning of the month regarding toothpaste bombs. Much like the shoe bomb warning, officials said there wasn't an actual plot that was uncovered, but rather were simply warning after monitoring intelligence they had received.

One counter-terrorism official had said at the time that there were "specific threats" being monitored ahead of the Sochi Winter Olympics, relation to Muslim fundamentalists.

Today notes that back in December 2001, Richard Reid tried to set off explosives that he had hidden in his shoes during an international flight, but was caught by fellow passengers in time.