NEWARK - Airline passengers may notice additional security in the airport screening area this week after Homeland Security issued a warning to look out for hidden explosives.

Federal officials asked airlines to be vigilant against possible shoe bomb plots after intelligence indicated someone may try to smuggle one onto a U.S.-bound flight. 

Passengers like Susan Fox, of Weehawken, say it's better to be safe than sorry. "I travel quite a bit," she says. "So I always have to be concerned about things like that." 

Officials have not released any information on what airline could be involved, what country the flight would come from, or when such an attack might take place. 

It's been common practice to have passengers remove their shoes at security check points, before boarding their flights, since 2001 when passengers prevented a British citizen named Richard Reid from igniting such a device on a flight from Paris to Miami. 

Just days before the opening of the Winter Olympics in Sochi, Homeland Security warned airlines flying to Russia to be on the alert for explosive devices that could be hidden inside toothpaste. As a result, the Transportation Security Administration banned passengers from bringing any liquids in carry-on luggage on nonstop flights from the U.S. to Russia. 

It is unclear if the latest warning is related to the threats to Russia-bound flights.

Sources say Homeland Security issued the shoe bomb warning out of an abundance of caution and not because of a specific threat.