This article was originally posted at National Review.

President Donald Trump’s decision last week to order airstrikes to punish Syria for a chemical-weapons attack that killed and injured scores of civilians has exposed conservatism’s intellectual confusion about U.S. foreign policy. Perhaps the most troubling thing about this debate is the deficit of historical perspective – a failure to consider the moral-theological tradition of the West that insists that civilized nations have a responsibility to protect civilian populations in times of war.

Amid the brutally destructive Wars of Religion, Protestant thinker Hugo Grotius wrote On Laws of War and Peace (1625). “Though there may be circumstances, in which absolute justice will not condemn the sacrifice of lives in war,” he argued, “yet humanity will require that the greatest precaution should be used against involving the innocent in danger, except in cases of extreme urgency and utility.”

Here is a political principle, rooted in Judeo-Christian ethics, which has helped to protect countless civilians from the savagery of war. Here is a concept about human dignity that has influenced every international document on the conduct of nations in wartime: from the Geneva Protocol (1925), banning the use of chemical weapons; to the Genocide Convention (1948), adopted in the aftermath of the Holocaust; to the United Nations Responsibility to Protect (2005), a resolution authorizing military force to prevent crimes against humanity.

Yet many of the critics of the U.S. missile strike seem indifferent to this tradition. Conservatives such as Andrew McCarthy argue that Bashar al-Assad’s use of a weapon of mass destruction — which targeted innocent men, women, and children — involved “no vital American interests.” No vital American interests? When did conservatism decide that the United States has no interest in upholding a universal moral norm that has helped to prevent the West from descending into a permanent state of barbarism? When, exactly, did the humanitarian ideals of the Western tradition become irrelevant to the conduct of U.S. foreign policy?

It was the abject failure of the United Nations to uphold these principles throughout the 1980s and 1990s that produced the Responsibility to Protect (R2P) doctrine: the proposition that there is a collective responsibility to protect people from genocide, ethnic cleansing, and crimes against humanity — even if it means military intervention. Overwhelmingly approved by the U.N. General Assembly, R2P insists that nations cannot hide behind the U.N. charter and “national sovereignty” in order to wage war against their civilian populations. The signatories to the doctrine — which include the United States — agree to take “collective action . . . should peaceful means be inadequate” to protect populations at risk of gross human-rights abuses. In this, R2P pays homage to the Christian just-war tradition.

The problem, of course, is that the U.N. Security Council is deemed the only legitimate authority to implement the doctrine. Just-war theorist James Turner Johnson has written of the historic dysfunction of the United Nations in this regard: “The structure of the U.N. is such that clear purpose and effective command and control are virtually unimaginable.”

As long as Russia — Syria’s chief patron — retains its veto power on the U.N. Security Council, there will be no U.N. resolution to punish Assad or prevent him from committing more war crimes. Russian president Vladimir Putin has even suggested that the United States manufactured the chemical attack as a pretense for an invasion. We thus face the bizarre spectacle of a permanent member of the Security Council either complicit in a chemical-weapons attack or, at the very least, committed to a false and outlandish narrative of U.S. malevolence — all for the purpose of insulating a genocidal regime from censure. The result, if experience is any guide: an even more belligerent Syria, more mass atrocities, more attacks on humanitarian aid workers, and the near collapse of a universal moral principle.

And there are no vital American interests in play?

“If we are not able to enforce resolutions preventing the use of chemical weapons, what does that say about our effectiveness in this institution?” asked Nikki Haley, U.S. ambassador to the United Nations. “When the United Nations consistently fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action.”

Ambassador Haley has a good deal of U.S. diplomatic history on her side. The 1999 NATO intervention in Kosovo — a bombing campaign that brought an end to the ethnic cleansing of the Balkan wars — lacked U.N. approval. It was, to be sure, a controversial intervention, and Bill Clinton’s deep aversion to American casualties contributed to the carnage and chaos during the campaign. But political realists who saw no important U.S. interests at stake — not even naked aggression and a humanitarian disaster within Europe’s borders could stir them — looked morally bankrupt once peace and security were restored to the region.

The same can be said about the American and British intervention on behalf of Iraqi Kurds after the first Gulf War. The Kurds of northern Iraq rebelled against Saddam Hussein in 1991, after his army was defeated and kicked out of Kuwait by the U.S.-led coalition. But the Iraqi army cracked down on the rebels, and seemed ready to exterminate the entire population — having used chemical weapons against them with impunity during the Iran–Iraq war. Within weeks, a million Kurds fled the region, with nearly 1,000 people dying each day.

The U.N. Security Council approved humanitarian assistance for the Kurds, but it never authorized the no-fly zones established under President George H. W. Bush. From April to September 1991, Operation Provide Comfort flew over 40,000 sorties, relocated 700,000 refugees, and restored many Kurdish villages destroyed by the Iraqi military. Over the next decade, U.S. and British pilots took anti-aircraft fire from Iraqi forces, shot down Iraqi planes, and successfully defended the no-fly zones. Today the Iraqi Kurds are among the most pro-Western allies in the Middle East, and arguably the most effective fighting force against the Islamic State. Their survival and contribution to stability in the region was the result of a humanitarian mission that, according to the realists, involved no vital American interests.

In both instances, the United States drew upon insights embedded in centuries of moral and political philosophy. Conservatives ought to know and care about these ideas, which have done so much to promote international peace and security.

President Trump’s decision to put aside his “America First” campaign pledge and to punish the Assad regime will not solve the nearly intractable problem of the Syrian civil war. The airstrike, confined to a single Syrian airfield, has hardly affected Assad’s capacity to deploy chemical weapons. But Trump’s decision to act, if part of a broader strategy of engagement, has the potential to reverse the diplomatic disaster created by Barack Obama’s feckless and disingenuous policies in Syria. It might help secure a measure of justice where diplomacy, absent the projection of American power, has utterly failed.

The United States has sent a message that lawless regimes cannot always evade the moral laws that govern civilized nations. It is a message that is consistent with America’s vital national interests — and with its most cherished political and religious ideals.

Joseph Loconte is an associate professor of history at the King’s College in New York City and the author of A Hobbit, a Wardrobe, and a Great War: How J.R.R. Tolkien and C.S. Lewis Rediscovered Faith, Friendship, and Heroism in the Cataclysm of 1914-1918.