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U.S.: Terrorists may surgically implant bombs

Updated at 1:47 p.m. ET

WASHINGTON - The U.S. government has warned domestic and international airlines that some terrorists are considering surgically implanting explosives into humans to carry out attacks.

A law enforcement source told CBS News that al Qaeda's Yemeni chapter, al Qaeda in the Arabian Peninsula, indicated in information, obtained by the intelligence community in recent months, an interest in recruiting a surgeon to implant explosives in the body of a suicide bomber to circumvent airport detection equipment and detonate an explosive device on an aircraft, investigative producer Pat Milton reports.

The source said that the sense is that the threat was "aspirational and not a hard threat." However, officials are concerned that some kind of plot is in the works by the Yemeni group, Milton reports. The law enforcement source told CBS News they feel the United States is due for an attempted attack.

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There is no intelligence pointing to a specific plot, but the U.S. shared its concerns last week with executives at domestic and international carriers, The Associated Press reported.

The intelligence on the interest in recruiting a surgeon, coupled with the Yemeni group's stated goal of getting past intrusive airport screening to set off a bomb on an airliner, a goal that has been discussed openly in the group's online magazine Inspire, led officials to put out an advisory, Milton reports.

Specifically, security personnel are being told to be aware of someone who may be acting unusual possibly due to an inserted device, which may be causing discomfort or pain.

The law enforcement source told CBS News that officials believe that the implantation tactic would be challenging for terrorists to successfully carry out.

They are aware of the 2009 attempt on the life of Saudi Prince Muhammad bin Nayef, head of Saudi Arabia's counterterrorism operations, Milton reports. In that botched attempt, a Qaeda suicide bomber -- one of Saudi Arabia's most wanted men -- inserted a pound of explosives and a detonator into his rectum and avoided detection by two sets of airport security equipment. The bomb exploded as the bomber met with the prince in a prearranged meeting, slightly injuring the prince but killing the bomber.

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People traveling to the U.S. from overseas may experience additional screening at airports because of the threat, according to the Transportation Security Administration.

"These measures are designed to be unpredictable, so passengers should not expect to see the same activity at every international airport," TSA spokesman Nick 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."

Placing explosives and explosive components inside humans to hide bombs and evade security measures is not a new idea. But there is new intelligence pointing to a fresh interest in using this tactic, a U.S. security official told the AP. The official spoke on condition of anonymity to discuss sensitive security information.

When the U.S. government receives information suggesting terror tactics that could threaten commercial aviation, the TSA alerts companies domestically and abroad. Last December, the U.S. received intelligence that al Qaeda's Yemen branch was considering hiding explosives inside insulated beverage containers to carry them on airplanes. That warning was shared with domestic and foreign airlines so that security could be on the lookout, even though there was no specific plot.

Airport security has increased markedly since the Sept. 11, 2001, terror attacks. But terrorists remain interested in attacking aviation and continue to adapt to the new security measures by trying to develop ways to circumvent them.

The law enforcement source told CBS News that the Yemeni group has not been as disrupted as al Qaeda, Milton reports. The group has been suspiciously quiet in recent months, and summertime seems to be a popular time for terrorists to launch an attack.

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Last month, the chairman of the House Intelligence Committee said May's killing of Osama bin Laden hasn't cut down on al Qaeda's drive to carry out terror attacks within the United States.

The chairman, Republican Michigan Rep. Mike Rogers, issued such a warning about al Qaeda in the Arabian Peninsula.

"Al Qaeda in the Arabian Peninsula is strictly, or has been strictly focused on attacks in the U.S. homeland," Rogers told ABC News. "This morning, when you're over your breakfast cereal there is somebody in Al Qaeda in the Arabian Peninsula planning another attack in the U.S."

In the files that U.S. Navy SEALs recovered from bin Laden's Pakistani compound May 2, the intelligence community found further information that bin Laden urged his supporters to carry out attacks within U.S. borders, ABC reported.

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Also, The Associated Press has reported that bin Laden supported the Yemeni group's focus on smaller operations. According to bin Laden's private journal, he had urged Qaeda operatives to broaden its focus of U.S. targets to include smaller cities and other means of mass transportation such as trains instead of commercial airliners, the AP reported.

Al Qaeda in the Arabian Peninsula has been linked to three specific incidents in the past two years: the Fort Hood shooting massacre allegedly carried out by Army psychologist Maj. Nidal Malik Hasan, the attempted bombing of a commercial airliner over Detroit on Christmas Day and the foiled plot to detonate bombs hidden inside computer printers on planes over the United States.

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