Those who have expressed grim satisfaction at the reports of assassinations of Iranian nuclear scientists have been told they will sing a different tune if Israelis or Jews are targeted by Iran. Today’s news of attacks on the Israeli embassies in Georgia and India will, no doubt, lead some to assume those responsible are in some way taking revenge for the Iranians. But the assumption that Israel is reaping what it sowed is off the mark. So, too, is the attempt by Israel’s critics on both the right and the left to claim there is some moral equivalence between Israel and Iran.

The first problem with this equation is that Iran and its various terrorist auxiliaries need no new excuse to attack Israelis or Jews. Groups like Hamas and Hezbollah have been doing this for many years. When it comes to the question of whether or when Iran, Hamas and Hezbollah will strike, the assumption ought to be they are doing their worst at all times. Second, and more important, is that squeamishness about the attacks on Iranian scientists is entirely misplaced if not completely disingenuous.

Last week, I wrote about the NBC news report about Israel’s alleged employment of an Iranian dissident group to help carry out covert operations inside the Islamic state. The group, the People’s Mujahedin of Iran (also known by their Farsi acronym MEK) has been labeled a terrorist organization by the United States. Some prominent Americans on both sides of the aisle dispute this label. Others have told me in the last week  they doubt the veracity of NBC’s allegations. I took no position on the virtues of the MEK or on the quality of NBC’s reporting. What I did say was because Israel is locked in a war with Iran in which its existence is at stake, the use of the Iranian’s regime’s enemies to aid operations designed to forestall a nuclear threat is justified.

This provoked angry denunciations of my position from both the left by Glenn Greenwald at Salon and Robert Wright at The Atlantic, and the paleo right by Daniel Larison at the American Conservative. All seem to agree Israel’s alleged use of the MEK to kill Iranian scientists is an act of terrorism, and this makes Israel a state sponsor of terrorism. They also believe it is terribly hypocritical of those of us who denounce terrorist attacks on Jews and Israelis to think it is okay to knock off those working on Iran’s nuclear program.

This stance is not so much based on a devotion to an inflexible legal definition of terror as it is with delegitimizing concern about threats to Israel’s existence. Larison writes that a belief an Iranian nuclear weapon “has something to do with averting a second Holocaust … is a deeply irrational and unfounded assumption.” He bases that on the fact that Israel has nuclear weapons and this nuclear deterrent should put to bed any worries about Iran’s leadership thinking about a first strike on the Jewish state. Thus, in his view, any attempt to stop the Iranians from having the capacity to kill millions in a single stroke is just a criminal endeavor spurred on by an Israeli “fantasy” about Iran’s intentions.

But one needn’t step into the world of fantasy to understand what Iran’s intentions might be toward Israel. Their leaders spell it out, leaving little to the imagination. As Iran’s Supreme Leader Ayatollah Khamenei said earlier this month while defending his country’s nuclear ambitions, Israel is a “cancer” that must be removed from the region. There is an interesting debate as to whether the fanatical religious figures who run Iran are prepared to risk attacks in kind from Israel should they use nukes to make good on their threats. But while it is not possible to predict Iran’s conduct in advance with certitude, the notion that Israel should simply sit back and wait and see what will happen while a government that actively promotes anti-Semitism acts on their threats is not advice any rational or responsible government can take when the lives of millions of citizens are at stake.

Above all, what Greenwald, Wright and Larison have a problem with is the entire idea of drawing a moral distinction between Iran and Israel. That is why their entire approach to the question of the legality of Israel’s attacks is morally bankrupt. Underneath their preening about the use of terrorists, what Greenwald, Wright and Larison are aiming at is the delegitimization of the right of Israel — or any democratic state threatened by Islamist terrorists and their state sponsors — to defend itself. They do so by dismissing the idea there is any credible threat to Israel and then by labeling those who are using their expertise to put a genocidal weapon in the hands of those who have made repeated threats of genocide as innocent civilians. However, at this point, doubts expressed about Iran’s intentions are mere sophistry cynically taken up by those who wish to hamstring the effort to avert a catastrophe.

Undeclared wars, even those between evil regimes and democracies, are necessarily messy. But the idea that the United States or Israel must forebear from acting in defense of humanity against a regime such as that of Iran because the Iranian scientists have not been convicted in a court of law is a moral absurdity. Contrary to the disingenuous arguments of Iran’s intellectual defenders, it really is quite easy to make a distinction between an Iranian nuclear scientist and an innocent American, Israeli or Jewish victim of the anti-Semitic terror sponsored by that regime. Greenwald, Wright and Larison are unmoved by the prospect of Khamenei having his finger on a nuclear button and are aghast at Israel’s resort to cloak and dagger methods to avert the possibility. But the only really immoral thing for either the United States or Israel to do is to fail to act.