F. Michael Maloof, formerly with the Pentagon's Technology Security Operations, writes:

WASHINGTON – The Boston Marathon bombing that killed three people and wounded more than 180 was on the same day as the 101st anniversary of the birthday of North Korean founder Kim Il Sung, raising questions among analysts whether Pyongyang, as in some of its past terrorism, used proxies to carry out the attack in the U.S.

North Korea in recent weeks has been threatening the U.S. with attacks, including a pre-emptive nuclear strike. Pyongyang also has a history of committing terrorist attacks without taking credit for them.

I'm not saying that's it, but until more definite information is in, it's a line of inquiry.

Don Firth