President Donald Trump’s decision to bomb Iran’s nuclear weapons facilities has generated all the right critics — Senator Chuck Schumer (D-N.Y.), Rep. Nancy Pelosi (D-Calif.), U.N. Secretary-General Antonio Guterres — but the sheer volume of criticism may create doubts in many Americans’ minds. Christians must subject acts of war to an even higher standard of moral scrutiny, as we not only require wars to be appropriate to American interests, but also morally justified, according to principles deduced from Scripture.

On June 13, this author outlined “6 Reasons Why Israel’s Strike against Iran Was Justified,” according to traditional Christian principles of just war. The recent U.S. strike on Iran’s nuclear program is justifiable on largely the same grounds, and that article remains relevant for those who seek a big-picture overview.

But U.S. military engagement against Iran has likely intensified the stakes in the minds of American Christians, sharpening into one question that demands a much more particular response. Many readers may find themselves asking the question: how can a preemptive military strike be justified as self-defense?

This is a worthy question. Righteous wars require a just cause and a right intention. Wars of conquest are wrong, but wars of self-defense are right — provided other conditions are met. Intuitively, we understand that simply wanting to beat up on another country cannot be justified on grounds of self-defense. If it were that simple, reason tells us, then every warmonger would abuse the principle to justify his ambition — as Vladimir Putin has sought to do with regard to Ukraine.

It is much easier to prove self-defense if the other party struck first. But this does not eliminate the category of first-strike self-defense. A policeman may shoot a man charging him with a knife without allowing himself to be stabbed first. Mosaic case law permitted a homeowner to use lethal force in self-defense against a night intruder (Exodus 22:2-3).

In the case of the Iranian regime, the justification for a preemptive strike lies in the unrivalled destructive power of the nuclear weapons the regime was actively pursuing.

An exploding nuclear bomb releases lethal radiation stretching to nearly a mile in diameter. It releases superheated air hotter than the sun’s core, which vaporizes nearby objects and causes severe burns up to 20 miles away, in a matter of seconds. It releases a blast wave that can flatten most buildings for miles. Besides these nearly immediate effects, a nuclear explosion also causes radioactive fallout, which can render an area uninhabitable for years to come.

In other words, a single nuclear bomb can more-or-less destroy a medium-sized city. For instance, Tel Aviv (with an area of 20 square miles and a population of nearly half a million) or Jerusalem (with an area of nearly 50 miles and a population of roughly a million) would be basically destroyed by a single nuclear weapon. (Rough American equivalents to these cities would be Miami and San Francisco.) Iran had enough enriched uranium for 10 nuclear weapons, the International Atomic Energy Agency reported on May 31, and its stockpile was growing by nearly 50% every three months.

Because of the death and devastation nuclear weapons can cause, a responsible government that cares about protecting the lives of its people can simply not afford to allow its sworn enemy to obtain such a weapon. The destruction of a single nuclear bomb would make the deliberate terrorist massacres of 9/11 or October 7 look like amateur hour. Especially for a geographically small nation like Israel, a barrage of nuclear weapons could effectively destroy the entire nation.

To this, the thoughtful reader will likely raise a historical objection. The latter half of the 20th century was defined (literally, in the term “Cold War Era”) by adversarial powers, who each possessed large stockpiles of nuclear weapons, and who never once fired those weapons upon each other. Although tense at times, the respective leaders of the U.S.A. and the U.S.S.R. refrained from nuclear warfare because they rationally calculated that their opponent could retaliate in like manner, resulting in a loss of life that would be utterly abhorrent. Although not ideal, the prospect of “Mutually Assured Destruction” (M.A.D.) created decades of peace (at least between the principals, although they still engaged in proxy wars).

This objection is correct, and the logic of M.A.D. still informs interactions among great powers today.

However, this logic does not hold true with regard to the current Iranian regime. As National Review’s Andrew McCarthy put it, “Iran’s regime is a millenarian jihadist vanguard that defines itself by its hatred of the United States, Israel, and the West — ‘Death to America, Death to Israel’ is a policy, not a slogan.”

The Iranian regime has provided abundant evidence to suggest that it cares nothing for the lives of its people, so long as it achieves the annihilation of Israel. Every sanction, every threatened attack, and every actual attack by Israel failed to dissuade the Iranian regime from its purpose. If this is true, and if Iran had nearly completed a nuclear weapon, the conclusion is that, once Iran obtained a nuclear weapon, nothing would prevent it from using that weapon against Israel. The logic of M.A.D. provides no deterrent to a suicide bomber.

The thoughtful reader may also raise a logical objection. This reasoning may hold true for Israel, they might say, but the United States is not Israel; since the U.S. faces no threat of imminent annihilation by Iran, it cannot justify a pre-emptive strike against Iran. Indeed, this has been the argument of Senator Chris Murphy (D-Conn.) and others in Congress.

There are multiple responses to this objection. First, the Iranian regime holds enmity towards America as a fundamental ideological tenet. Although Israel may be the “Little Satan” it attacks first, it would gladly focus on America, the “Great Satan,” if Israel were destroyed. Even from an “America First” perspective, keeping our nation’s adversaries as far away from our homeland as possible is wise.

Second, the fact remains that Iran’s nuclear weapons program posed an imminent threat to Israel’s survival. If it is just for someone to use force in defense of his own life, so it is just for another party (with proper authority) to defend him. Thus, the sniper is justified in shooting the criminal holding a gun to his hostage’s head. The basic principle at play is that a lawful authority may justly use force to preserve innocent human life.

By removing a catastrophic weapon from the hands of a regime like Iran, the U.S. has done both itself and the world a huge favor.