Terrorists intent on striking commercial aircraft have shown renewed interest in surgically implanting explosives or explosive components in humans to conduct attacks, a U.S. security official tells CNN.
The idea of implanting bombs has been discussed in the past, but the United States has obtained fresh intelligence about the desire of terrorists, and there is new intelligence about a possible technique that could be used, according to the official, who declined to elaborate.
Last week, U.S. officials briefed airlines and U.S. allies overseas about new intelligence, a Transportation Security Administration spokesman said.
The Department of Homeland Security and the TSA recently notified them that "recent intelligence" indicates "the continued interest of terrorists to target aviation," said the spokesman, Nicholas Kimball.
"Terrorist groups have repeatedly and publicly indicated interest in pursuing ways to further conceal explosives" because of advances in aviation security, he said.
"As a precaution, passengers flying from international locations to U.S. destinations may notice additional security measures in place. These measures are designed to be unpredictable, so passengers should not expect to see the same activity at every international airport," Kimball said.
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, he said.
Full-body scanners, or what the TSA calls "Advanced Imaging Technology," cannot detect items inserted in bodies. But the machines can help screeners detect alterations to body contours, which can be a clue that someone may be concealing a bomb.
The TSA also notes that AIT is just one of many layers in security that include intelligence, canines, and behavior detection officers, all of whom could contribute to catching a person concealing a weapon or bomb.