The White House said Wednesday there was no danger of an imminent attack on airplanes after reports that terror groups were mulling implanting bombs into the bodies of passengers.
The assurances came after news that the US administration warned airlines that extremist groups were considering surgically implanting explosives into people to try to beat tight airport security measures.
Passengers flying to the United States could now face even tougher screening measures, a spokesman for the Transportation Security Administration, Nicholas Kimball, told the Los Angeles Times.
"These measures are designed to be unpredictable, so passengers should not expect to see the same activity at every international airport," Kimball said, adding existing methods could not detect plastic explosives under the skin.
"Measures may include interaction with passengers, in addition to the use of other screening methods such as pat-downs and the use of enhanced tools and technologies."
White House spokesman Jay Carney confirmed that officials from Homeland Security and the TSA had been in contact with airlines.
"The action they took in briefing air carriers and foreign partners to provide greater insights into recent intelligence indicating continued interest of terrorists to target aviation did not relate to an imminent or specific threat," he said.
"Terrorist groups have repeatedly and publicly indicated interest in pursuing ways to further conceal explosives and we continue to evolve just as the threat does," he added.
"In other words, this is the idea that terrorists have been looking for other ways to circumvent security measures in order to target aircraft. It's not at all surprising."
American Airlines and US Airways refused to comment.
But security at US airports has been ramped up over the past decade since Al-Qaeda militants hijacked four US planes on September 11, 2001 and plowed two of them into the World Trade Center in New York.
A third plane hit the Pentagon in Washington, and the fourth crashed into a Pennsylvania field after the passengers overcame the hijackers.
There have been several attempts to blow up US-bound airlines, including on Christmas Day 2009 when a Nigerian man was arrested for allegedly carrying plastics explosives stitched into his underwear which he planned to ignite on a flight from Amsterdam to Detroit.
The trial of Umar Farouk Abdulmutallab on terror charges is set to begin in October.