Tit for Tat?

So, let me see if I’ve got this straight.  Israel kills Iranian nuclear scientists in an effort to slow Iran’s efforts to develop nuclear weapons, weapons they’ve promised to use to destroy Israel.  Iran responds by killing Israeli TOURISTS.  An American official describes this as “Tit for tat.”  Of course the Obama Administration quickly condemns the targeting of innocent civilians in the strongest terms, right?  Well, the American ambassador to Bulgaria did express our “outrage and horror”   But the report contains no comment by Obama or Clinton.  And, of course, the New York Times does not offer the slightest criticism itself, though it does duly report the Iranian government’s hypocritical condemnation of its own actions.  What should the American government do in response to such terrorist acts?  And, while we are at it, what should the American government do about the Iranian development of nuclear weapons?  Does Romney have a plan?  Does anyone?