Are Pre-Emptive Strikes Morally Permissible?
Some claim not, but both the law and ethics of self-defense say they can be.
The tweet bugged me. A prominent Catholic magazine editor claimed that, “If you are Catholic, you can’t morally justify ‘preemptive’ strikes,” presumably due to current international law.
He was referring, of course, to Israel’s then-recent attack on Iranian nuclear research facilities and researchers.
It stopped me.
My first reaction was, Huh? So I wrote this:
The more I thought about it, the more problematic this fellow’s claim seemed to be. (To be fair, he’s a great guy and is right on many issues… but just not on this one.)
The fact is, the right to “strike first” if facing an imminent, credible threat is recognized not merely under common and statutory law (although it varies by state) but also by both philosophical and Catholic ethics.
In the United States, self-defense laws generally allow persons to use force — including striking first — if they reasonably believe it is necessary to protect themselves from imminent harm.
The Right of Self-Defense
The legality of striking first depends on the specific circumstances and the laws of the state where the incident occurs.
You must have a reasonable belief that you are in imminent danger of unlawful force or harm.
This means the threat must be immediate and credible, such as an assailant making explicit threats and reaching for a weapon.
In addition, the force used in self-defense must be proportional to the threat faced.
If the assailant appears to be reaching for a weapon after making threats, striking first may be justified if a reasonable person would believe they were about to be attacked with deadly force.
It’s true that some states require you to retreat, if safely possible, before using force, especially deadly force.
But other states, such as Georgia and Florida, have “stand your ground” laws that remove the duty to retreat if you are lawfully present and reasonably believe that force is necessary to prevent harm to yourself or others.
It goes without saying that no one should get into a complicated legal situation if it can be avoided.
But the point is, it can be legal under U.S. law to strike first in self-defense if you reasonably believe you are facing an imminent threat of harm, such as when an assailant makes verbal threats and reaches for a weapon.
Justified by Secular and Catholic Ethics
What’s more, pre-emptive strikes can also just justified by both secular ethics and Catholic moral teaching.
Many philosophers argue that striking first can be considered morally permissible if it is the only way to avert a specific, credible, and imminent attack.
Some philosophers distinguish between,
… pre-emptive self-defense (striking first when an attack is imminent), which is generally considered morally justified; and
… preventive self-defense (striking first to prevent a possible future attack that is not imminent) which is usually regarded as morally impermissible.
Even under the stricter principles of Catholic moral teaching, pre-emptive self-defense can be seen as sometimes justifiable.
For example, a police officer has a right, even a duty, to deploy deadly force if a suspect is reaching for a weapon — in effect, striking first — if the suspect presents an imminent threat to himself and to those he is sworn to protect.
The Church has long taught that it is morally permissible to defend one's own life or the lives of others against unjust aggression.
In fact, the Catechism of the Catholic Church teaches that self-defense “can be not only a right but a grave duty for one who is responsible for the lives of others (CCC 2265).”
Catholics are called to be peacemakers and to avoid violence whenever possible. If there is a non-violent way to avoid harm, that path must be chosen.
If it is possible to escape or de-escalate without violence, one is morally obligated to do so. Lethal force is justified only if it is the only means to preserve life.
The direct intention must be to preserve life, not to harm or kill the aggressor.
If the aggressor is harmed or killed as an unintended side effect of necessary defense, this can be morally permissible — even if a defender must act first to stop what appears to be an imminent attack.
If a person reasonably believes that an aggressor is about to inflict serious harm (for example, reaching for a weapon after making threats), striking first may be morally justifiable, provided the response is necessary and proportionate to prevent harm.
What About Nation States?
Can countries strike first if they believe they are about to be attacked?
That’s more complicated.
Under current international law, the right of pre-emptive self-defense for nation states is not explicitly recognized in any treaty, including the UN Charter, except in very limited circumstances.
The so-called Caroline test — a reference to a U.S. cargo ship in 1837 that was attacked by British forces which believed it was supplying rebel forces in Canada — established that pre-emptive self-defense is only justified if the necessity is “instant, overwhelming, leaving no choice of means, and no moment for deliberation.”
This standard is widely cited as the customary law threshold for anticipatory (pre-emptive) self-defense, but it sets a very high bar: the threat must be imminent and unavoidable.
Is Israel facing such a threat from Iran’s nuclear weapons program?
I have no idea.
We learned from the Iraq War that intelligence services are notoriously inept if not duplicitous.
They claimed, falsely, that Saddam Hussein had an advanced nuclear weapons and WMD program, and that was the entire justification for the Iraq War — which caused the deaths of 4,500 American soldiers and between 200,000 and 600,000 Iraqi civilians.
As a result, the public, especially the American public, has every right to be skeptical of claims from any nation’s so-called intelligence service about imminent threats and nuclear weapons.
For this reason, I believe two things are true.
First, if Israel truly does believe it’s facing an imminent nuclear attack from a nation that has repeatedly sworn to destroy them, then, yes, even under the narrow terms of the Caroline case, it has both the moral and legal right and the duty to protect itself, so long as its response is proportional to the threat and it uses the minimum amount of force necessary.
There is plenty of anecdotal evidence that Iran’s leadership does want Israel destroyed. In 2024, Iranian Major General Abdolrahim Mousavi, Commander of Iran’s Army, stated:
"The Army will move hand in hand with the IRGC so that the arrogant system will collapse and the Zionist regime will be annihilated.”
Second, America, which is not threatened by Iran, has the right to avoid entanglement in yet another endless foreign war.
This, to me, is the sane America First view.
It both respects Israel’s right to defend itself and the right of America’s citizens to stay out of the “foreign entanglements” our forefathers, such as George Washington, warned us against.
Robert J. Hutchinson is the author of numerous books of popular history, including Searching for Jesus: New Discoveries in the Quest for Jesus of Nazareth (Thomas Nelson), The Dawn of Christianity (Thomas Nelson), The Politically Incorrect Guide to the Bible (Regnery) and When in Rome: A Journal of Life in Vatican City (Doubleday). Email him at: roberthutchinson@substack.com.