When 32-year-old Iranian nuclear scientist Mostafa Ahmadi-Roshan was assassinated in a car bomb attack Wednesday, Iran immediately accused Israel of carrying out the attack. At this point, it's increasingly difficult to argue to the contrary.

Without question, a number of aspects of yesterday's attack remain mysterious and warrant a skeptical review of Iran's account, which it is taking to the United Nations. For instance, how were no culprits found when the alleged motorcyclist planted a magnetic bomb under a scientist's car in broad daylight with several witnesses present? This isn't even the first time such an attack has happened amid busy, rush-hour traffic. Another thing to keep in mind: Israel isn't the only state opposed to Iran's nuclear advancement: Sunni Arab governments could have also waged the attack. And finally, some of Iran's nuclear scientists who have been assassinated had ties to opposition groups and may have been targeted by Iran's own government. The preponderance of evidence, however, suggests Israel carried out the attack, with the possible assistance of the U.S.