Brennan says cargo plane explosives could detonate on their own

WASHINGTON (CNN) - Explosive devices in cargo packages addressed to Chicago, Illinois, destinations appear to have been designed to detonate on their own, without someone having to set them off, the top White House counterterrorism official told CNN on Sunday.

John Brennan, President Barack Obama's assistant for homeland security and counterterrorism, said on CNN's "State of the Union" program that the sophisticated explosives could have been intended to blow up the air cargo planes carrying them, as suspected by British authorities.

"It is my understanding that these devices did not need somebody to detonate them," Brennan said, adding that U.S. authorities continued to investigate.

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