U.S. sources told Reuter's that newly discovered intellegence indicates that sophicated bomb makers may have come up with new bomb design innovations to evade airport security measures.
The U.S. sources said the warnings were sent to airlines flying to the U.S. from around thirty airports in Europe, the Middle East and Africa. Among the airports where airlines were a hightened security presence is on alert for possible shoe bombs include Amsterdam's Schiphol, London's Heathrow and Gatwick, and the airport in Manchester, England.
Two months after the 9/11 terrorist attacks, the infamous "shoe-bomber," Richard Reid managed to fly under the radar of airport security with PETN, a liquid explosive hidden in the soles of his shoes and boarded American Airlines Flight 63 from Paris to Miami on December 22, 2001.
Alert passengers and crew members witnessed Reid trying to light a fuse and restrained him by tying him to his seat until the flight, which was diverted to Boston. FBI bomb technicians and explosives experts later discovered the PETN explosives in Reid's shoes.
Richard Reid, a self identified member of al-Qaeda pleaded guilty to terrorism charges in October 2002 and is currently serving a life sentence at a super-maximum security prison in Florence, Colorado.
International terrorism experts and U.S. Department of Homeland Security officials have increasingly expressed concerns over the al-Qaeda branch in Yemen, due to the group's technically-savvy bomb-making technicians.
Among the top leaders of Al Qaeda in Yemen, also known as Al Qaeda in the Arabian Peninsula is a Saudi bomb-making expert identified as Ibrahim Hassan Al-Asiri, the man believed to have constructed the explosive device sewn into the underwear of a suicide bomber who attempted to detonate the device during a Christmas Day 2009 flight over Detroit.
Al-Asiri, a 31-year old college drop out is also believed to have designed the October 2010 "printer bombs" discovered on cargo planes which originated in Yemen, and were intercepted in Mumbai and the U.K. after receiving a detailed tip from Saudi officials, before arriving at their final destination in Chicago, Illinois.
Al-Qaeda's expansion to the Arabian Peninsula is believed to have revived the terrorist organization after the death of Osama bin Laden in May, 2011. Terrorism experts say highly skilled bomb makers and technology saavy innovators have made the Yemen branch the largest threat to U.S. security.
The TSA claims to employ a variety of security measures to thwart future shoe bomb attemps.
The best bet? Stay alert airline passengers and crews!