WASHINGTON — If the United States were confident that North Korea had succeeded (or would very soon) in constructing a fully functional nuclear-armed intercontinental ballistic missile (ICBM) that could target the United States, would a military first strike by the U.S. be morally justified?

The Church’s framework for thinking about the just use of military force and the facts as publicly known right now suggest that the answer is No.

After last month’s test of a KN-20 missile, North Korea now does seem to have a functional ICBM with a range to strike the continental United States; it has probably also successfully miniaturized some of its between 20 and 60 atomic warheads so that they can be placed on top of a missile. What they may not have yet solved is the problem of shrouding the warheads in such a way that they can survive re-entry into the atmosphere, a necessity for intercontinental flight.

The Washington Post recently reported that the Defense Intelligence Agency now believes that they will likely solve this problem and, therefore, have the ability to target the U.S. with a working nuclear weapon in less than a year. This combined with a torrent of bellicose rhetoric from North Korea’s dictator, Kim Jong Un — including a threat to fire a missile at Guam, a threat that appears since to have been withdrawn — make the situation increasingly dire and urgent. President Donald Trump has suggested at times that he will not allow North Korea to develop and deploy nuclear missiles, raising the possibility that the U.S. could unilaterally attack first.

Thus enters the question of the morality of a first strike. The traditional just-war framework that informs Catholic thinking about the use of military force has two parts: First, there are the so-called ius ad bellum (Latin for “right to war”) principles that speak to the conditions that allow for a just resort to arms. Second are ius in bello (Latin for “right in war”) principles that govern the conduct of war itself. In this column, I will broadly address the first principle, and then the second.

The Catechism of the Catholic Church summarizes just-war principles thus:

“Damage inflicted by the aggressor on the nation or community of nations must be lasting, grave and certain; all other means of putting an end to it must have been shown to be impractical or ineffective; there must be serious prospects of success; and the use of arms must not produce evils and disorders graver than the evil to be eliminated” (2309).

The first condition stated in the Catechism is a version of the traditional principle that war must have a “just cause” (a phrase that goes back to St. Thomas Aquinas). While the tradition is nearly unanimous in holding that self-defense against an actual attack constitutes just cause, many also recognize an attack on an ally or some atrocity perpetrated against any people (genocide, for example) as additional examples of a morally justifiable reason to take up arms.

But what about the threat of an attack combined with knowledge that the prospective enemy has or will soon have the capacity to inflict massive destruction?

There is a recognized distinction between “pre-emptive” military action and “preventive war.”

During the Cuban Missile Crisis in October 1962, Gen. Curtis LeMay, then chief of staff of the Air Force, opposed President John Kennedy’s naval blockade, calling instead for an outright air attack against Cuba, a policy he advocated even after the removal of Soviet missiles. This would have been an example of preventive war, a war initiated against an opponent who constitutes a dangerous threat but who has not attacked and absent any evidence of an imminent attack. An actual example of an act of preventive war was the Japanese attack on the U.S. Navy base at Pearl Harbor on Dec. 7, 1941.

Preventive war has almost always been condemned by just-war theorists and has never been approved in Catholic teaching.

Pre-emptive war, by contrast, involves the use of military force to prevent an attack that is believed to be imminent.

In 1967, Israel pre-emptively launched attacks on Egyptian airfields in response to Egypt’s closure of the Straits of Tiran and the mobilization of troops along its border. While opinion is divided, many accept this as a case of justified pre-emption.

The 2003 war against Iraq was defended at the time as pre-emption against what was said to be Saddam Hussein’s intent to use weapons of mass destruction against a number of countries. That case was certainly more debatable, and, in the end, we learned that Saddam’s threats were an unsuccessful bluff.

It was widely reported that the Vatican opposed the war in Iraq. Further, Pope Benedict XVI once explicitly repudiated the notion of “preventive war.”

In a November 2002 statement, the U.S. Conference of Catholic Bishops, while not endorsing the idea of pre-emptive war, did not categorically condemn it. Rather, the bishops outlined a very high bar for justifying pre-emption by requiring “clear and adequate evidence of an imminent attack of a grave nature.”

Do such imminent attacks exist with respect to North Korea?

Not at the moment. On Aug. 15, CIA Director Mike Pompeo told Fox News Sunday that “an attack from North Korea is not something that is imminent.” Secretary of State Rex Tillerson and the president’s national security adviser, Gen. H.R. McMaster, have made similar statements in recent days.

Beyond these recent assessments by public officials, however, one must consider the actual effects of a pre-emptive strike at North Korea that would require the application of the ius in bello part of just-war theory. Recall that the Catechism’s last condition for just war was that “the use of arms must not produce evils and disorders graver than the evil to be eliminated.” Both the Atlantic Monthly (July/August 2017) and The Economist (Aug. 5) recently assessed the probable consequences of an attack, and they are frightening indeed.

It seems highly unlikely that any military action strong enough to seriously set back Kim’s nuclear ambitions would go unanswered: The most obvious and immediate target for retaliation would be Seoul. The South Korean capital is a city of 10 million people (24 million if one considers the whole metropolitan area), and it is in range of thousands of North Korean artillery pieces, as well as short and intermediate range ballistic missiles, as are some 28,000 U.S. troops, not to mention Japan, which Kim has threatened before. Any strike would probably escalate quickly, and the casualties could be in the hundreds of thousands — mostly civilians.

Of course, a massive U.S. attack would cause enormous numbers of civilian casualties in the north and probably still not be sufficient to preclude at least some retaliatory attack on the south. Kim’s missile launchers and research facilities are dispersed and hidden around the country in ways that make any alleged “surgical” strike impossible.

The facts could, of course, change, and it is important to remember that the public does not have access to all the information at the disposal of political and military officials. An imminent attack by North Korea would not likely be a complete surprise, given the role of satellite surveillance and other intelligence capacities.

For now, it seems that the most prudent policy would aim at reducing tension, improving coordination with the region’s main power, China, and augmenting our defensive systems, like the Terminal High Altitude Area Defense (THAAD) and Patriot batteries already partially deployed in South Korea. The human costs of a second Korean War, even a brief one, could dwarf those of the first.


V. Bradley Lewis is an associate professor of philosophy at The Catholic University of America.