U.S. officials say they believe two packages bound for the United States contained the same powerful explosive used in the failed Christmas Day airline bombing.
The officials said full testing has not been completed but initial indications are the packages contained PETN, a chemical that was also a component of shoe bomber Richard Reid's explosive in 2001.
The packages were seized in Dubai and England on Friday. President Barack Obama called it a credible terrorist threat.
PETN is the primary ingredient in detonating cords used for industrial explosions and is popular among terrorist groups. It is a white powder. Officials have confirmed the package in England contained a white powder.