I don't think they see the US as a safer target; rather I think it the other way around. One attack on the US cost them control of two terror-sponsoring Muslim nations. Decades of attacks on Israel cost them nothing, which is why they keep doing it.
Time will tell. Al Queda is saying they have backpack nukes bought from Russia. Fox is trying to say they only have "nuclear materials".
Move along folks, nothing happening here...