Israel's official response to news of the assassination last week of Iranian nuclear scientist Mustafa Ahmadi Roshan was a deafening silence. The unofficial response was a wink. The day before, Israel Defense Forces Chief of Staff Lt. Gen. Benny Gantz, grinning slightly, spoke about "unnatural events" that were delaying Iran's nuclear program. The Israeli self-congratulation was obvious.

The Israeli public did not question the wisdom of assassinating the Iranian scientists. In Israeli culture, which sanctifies security, such questions are seen as treason. If the hit was successful - the scientist was eliminated and the assassins disappeared - you don't ask questions.

But U.S. Secretary of State Hillary Clinton insisted on calling a spade a spade: She categorically denied all U.S. involvement in the latest assassination and even declared that the United States emphatically opposed the assassination of scientists. Her announcement was received with shock and even dismay in Israel. Where is the wisdom in making this kind of public statement, some asked; and in any event, it's hypocritical in light of the fact that President Barack Obama has killed more terrorists using unmanned aerial vehicles than his predecessors.

In order to understand the American criticism of the hits on the scientists, one must ask the questions that Israelis avoid: Do such killings do real damage to Iran's nuclear program? What could be the negative results of the assassination policy? Is it right to create a situation in which scientists (first nuclear scientists and then perhaps scientists in general and senior officials ) become pawns in a war of assassinations and counter-assassinations?

Regarding efficacy, we know that Iran's nuclear program, based in Natanz, is an enormous project employing hundreds of scientists and thousand of technicians. It is hard to imagine that taking out a single scientist, however skilled and high-ranking, could damage the entire project enough to cause a significant delay. The project has long since passed the point where the fate of any one individual could affect it.

Not only will killing individuals fail to significantly delay the project or cause its leaders to dial back their political and strategic goals, it will almost certainly have the opposite effect: It will only add to Iran's determination to carry on. And to keep their scientists from becoming demoralized, the Iranians will do everything possible to make good on their promise of revenge.

If there are assassinations on one side, it must be assumed that there will be assassination attempts on the other side too. If Iranian scientists are not immune, then neither are scientists from the countries suspected of carrying out the assassinations. While Iranian officials had previously pointedly refrained from accusing any particular country, within hours of the attack this time, the government in Tehran and the Iranian media named Israel and the United States as the responsible parties, and promised revenge.

Israel may have rejoiced at the news of the hit, but let's consider how senior members of Israel's scientific community, especially the nuclear scientists, would view the assassination of scientists on the faculties of well-known academic institutions. (Most of the senior scientists in Iran's nuclear program also have academic posts. ) They would probably have reservations about the wisdom of expanding the shadow war to the scientific community.

Anyone who legitimizes the assassination of scientists in Tehran jeopardizes the personal security of scientists on the other side. The next phase of the assassination war is liable to turn international scientific conferences into arenas of assassination.

It is entirely possible that the damage caused by the assassinations far outweigh the benefits they bring.

The writer is a professor at the James Martin Center for Nonproliferation Studies, at California's Monterey Institute of International Studies, and author of "The Worst-Kept Secret: Israel's Bargain with the Bomb."

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