Hawaii’s embarrassing missile alert should remind Americans of the increasing price they may pay for treating the security of allies as if it were more important than their own security. The purpose of alliances should be to better protect the United States. Yet the defense commitment to South Korea soon could result in a nuclear attack on America’s homeland.

The “mutual defense treaty” with the Republic of Korea grows out of the Cold War, at a time when the United States and Soviet Union were competing globally. For America to lose anywhere in the world was seen as a Soviet victory. The ROK mattered not because the Korean Peninsula was inherently important for U.S. security, but because South Korea was part of the superpowers’ Great Game.

That ended with the collapse of the Soviet Union. Then the struggle between the two Koreas was just another regional confrontation. The costs of war would be higher than most local conflicts, but even so would not be unique: Iraq’s invasion of Iran and the collapse of Zaire (now the Democratic Republic of Congo) both unleashed extraordinary horror. Nevertheless, Washington never considered adjusting its Korean commitment and deployment to reflect America’s much-reduced stake.

Even more important, long ago the South raced past its northern antagonist. Today the ROK possesses roughly forty-five times the economic strength, twice the population, and a vast edge in technology, international status, global connections, and most every other measure of national power. It beggars belief that South Korea could not defend itself against its impoverished, isolated neighbor. And without the slightest chance that either China or Russia would back a North Korean invasion, Seoul does not require outside support.

So why does Washington continue to promise the full faith and credit of the United States—backed by Americans’ abundant wealth and lives—toward the South’s defense? Foreign policy should reflect an ever-evolving security environment. An American defense promise made in 1953 has little relevance to 2017. It is foolish to treat a treaty made more than six decades ago as permanent and unchangeable, irrespective of changing circumstances.

At least until now U.S. policymakers could comfort themselves that the conflict would be “over there,” to use Sen. Lindsey Graham’s infamous term. Those in uniform might die, but Americans could continue to count on invulnerability at home. That is no longer true.

If the Democratic People’s Republic of Korea makes a reliable ICBM, it will possess a nuclear deterrent capable of bringing the conflict “over here.” That is a particularly fearsome thought for policymakers used to sending the U.S. military around the globe spreading death and destruction to others. Now a “splendid little war” overseas could result in Americans sharing in the consequences.

There is no reason to believe that Pyongyang cannot be contained and deterred. But that isn’t a solution for official Washington, which is dedicated to attacking the North should circumstances warrant. That could be to help South Korea repel an attack. Or impose regime change, as the United States has frequently done elsewhere. The Trump administration is horrified by North Korea’s nuclear developments not because it expects Kim Jong-un to launch a suicidal assault on America. The administration is outraged that the DPRK would be in position to deter the United States. No longer could Washington fight the North without risking a devastating response.

The obvious solution is to turn the ROK’s defense back over to its own citizens. Let them deter the North from attacking. Protecting South Korea should mean more to South Koreans than Americans. And while the United States understandably desires to preserve peace in Northeast Asia, none of the reasons—humanitarian concerns, friendship with South Koreans, regional stability amid major Asian powers, and significant economic flows—warrant putting American cities at risk.

However, what if Kim Jong-un is bent on using nuclear weapons to forcibly reunify the peninsula, as the administration apparently claims? That’s a plausible objective, but it’s only speculation. Westerners so certain of Kim’s plans have never met him. Moreover, the Kims were evil but appeared to be realists: Kim Jong-un’s grandfather did not attempt again to conquer the South and his father did not try even once.

Today’s supreme leader has emphasized economic growth along with nuclear weapons, reflecting the Byungjin, or parallel development policy. In contrast, both his father and grandfather sacrificed economic success and popular comfort. In that sense, Kim has more at stake in maintaining peace, as much as he might dream about grabbing the rest of the peninsula.

Nor is there any reason to believe that Pyongyang cannot be deterred. Reunification wouldn’t mean much if the North’s capital, and most everything else of value in the DPRK, disappeared in a “lake of fire,” which the North Koreans have so often threatened to visit upon the South.

Today the United States provides the necessary nuclear deterrent. However, the North’s nuclear program raises the question whether the United States should remain in the middle of the Koreas’ violent quarrel. Especially when there is an obvious alternative, in this case a South Korean nuclear deterrent.

That’s not a good outcome, but then, the only good solution is the negotiated disarmament of the DPRK, which is the least likely result. In contrast, from Washington’s standpoint the worst outcome is to allow another country to hold America’s homeland hostage. But that is where present policy is leading.

Still, it might seem costless to bluff—until the hand was called. Then an administration would have to decide whether it was willing to risk the incineration of Honolulu—when missiles really were incoming—as well as Los Angeles, Seattle, San Francisco, Portland and other cities. For what? To protect a friendly nation, but not one critical to America’s security and unable to protect itself.

While a South Korean nuke would be a second best, so is every other policy toward North Korea. And a South Korean deterrent is less bad than other alternatives. It would destroy any illusion in Pyongyang that coercive reunification was possible. Prospective South Korean development of nuclear weapons also would encourage Beijing to do more to prevent North Korea from triggering proliferation that could spread to Tokyo and even, conceivably, Taipei. Finally, an ROK bomb is supported by two-thirds of South Koreans, many of whom reasonably doubt that, if pressed, an American president would risk the lives of hundreds of thousands or millions of Americans to defend the ROK.

In its policy toward North Korea the Trump administration has confused means and end. America’s alliance with the South was seen as a way to ultimately help keep Americans safe. That hasn’t been the case since the end of the Cold War. It certainly won’t be the case if North Korea develops the capacity to hit the American homeland.

But absent Washington’s threat to attack the DPRK, the latter has no reason to threaten the United States. Does Pyongyang contemplate aggression against South Korea? It’s hard to know, but it is Seoul’s job to defend the ROK. The Trump administration should phase out an alliance and deployment which risk resulting in the next missile warning issued by the Hawaii government becoming reality.

Doug Bandow is a Senior Fellow at the Cato Institute. A former Special Assistant to President Ronald Reagan, he is author of Tripwire: Korea and U.S. Foreign Policy in a Changed World and coauthor of The Korean Conundrum: America’s Troubled Relations with North and South Korea.

Image: A South Korean air force F-16 Fighting Falcon aircraft takes off for a sortie at Eielson Air Force Base, Alaska, Oct. 15, 2014, during Red Flag-Alaska 15-1. Red Flag-Alaska is a series of Pacific Air Forces commander-directed field training exercises for U.S. and partner nation forces, providing combined offensive counter-air, interdiction, close air support, and large force employment training in a simulated combat environment. (DoD photo by Senior Airman Peter Reft, U.S. Air Force/Released)​ / U.S. Department of Defense Flickr