The United States has not ruled out a connection between two Pakistani Americans, key Mumbai terror plotter David Coleman Headley and failed Times square bombing suspect Faisal Shahzad, as it probes all angles of the case.

"Well, it could be - there have been multiple plots that have involved the United States and Pakistan, citizens on both sides who have chosen to take these actions," a State Department spokesman said Friday when asked if there was any connection between the two cases.