Tighter security ordered for some U.S.-bound flights

The Obama administration is stepping up security for some flights headed to the United States from Europe and the Middle East, reflecting heightened concern that terrorists are developing more sophisticated bombs designed to avoid airport screening.

Homeland Security Secretary Jeh Johnson said in a statement that he has directed the Transportation Security Administration to “implement enhanced security measures in the coming days” at selected overseas airports.

“We will work to ensure these necessary steps pose as few disruptions to travelers as possible,” Johnson said in a statement. “We are sharing recent and relevant information with our foreign allies and are consulting the aviation industry.”

Specific steps or airports were not disclosed. A homeland security official said that TSA would work with airlines and security agencies overseas and that the changes will primarily focus on airports in Europe and the Middle East.

The effort does not involve changes to what travelers can take aboard flights. But passengers may see additional inspections of shoes and electronics, additional use of scanners designed to detect trace amounts of explosives, and another stage of screening at boarding gates, in some cases, the official said.

The measures do not involve U.S. domestic flights, and passengers could see changes as early as next week.

The changes came about based on new intelligence on terror groups trying to build new types of improvised explosives that are harder to detect, the official told CNN. There was no specific plot.

The UK Department for Transport confirmed Wednesday that it is stepping up some of its aviation security measures.

“For obvious reasons we will not be commenting in detail on those changes. The majority of passengers should not experience significant disruption,” a spokesman said.

“The UK has some of the most robust aviation security measures and we will continue to take all the steps necessary to ensure that public safety is maintained.”

Since hardening cockpit doors and taking other measures after the 9/11 al Qaeda attacks, the U.S. aviation security focus has shifted primarily from hijackings to plastic and other explosives that can be carried aboard a plane or hidden in baggage.

The United States has particularly been focused on efforts by al Qaeda in the Arabian Peninsula to develop undetectable explosives since the unsuccessful attempt by the so-called “underwear bomber” to bring down a Delta Air Lines jet over Detroit in 2009.

CNN’s Andrew Carey contributed to this report.