coming out of iran in the last week has been quite concerning. and to underscore that warning, clinton staying the straight is an international waterway and the u.s. and other nations are committed to keep it open, no matter what it takes, coming on the back of that very strong language denying any responsibility for those takedowns in iran, shep. shepard: all right. who else has this so-called covert campaign taken out, catherine. this is the most important part of the story. in virtually every case it s the same m.o. as today s hit. part of ongoing investigation into iran s nuclear program. the special unit has confirmed four scientists are dead since january of 2010. among them 50-year-old professor, an expert on nuclear energy at tehran s university who was killed when a bomb strapped to a motorcycle exploded outside his home in the iranian capital. he was considered one of iran s most important nuclear