Barely five years after World War II ended, the Korean War began. On June 25, 1950, the Democratic People’s Republic of Korea launched a full-scale invasion of the South, drawing in both the U.S. and China. The conflict ended essentially where it started, with an armistice. American troops still remain on station against the now nuclear North.

Until recently, U.S. involvement in a second Korean War would have meant horrendous conventional combat, but the damage would have been limited to forces on the Korean peninsula and nearby. Today, however, America’s homeland could be targeted by a nuclear attack. Nothing at stake is worth that risk. With the Republic of Korea capable of defending itself, Washington should formally end the conflict, drop its security guarantee, and bring home its forces.

As Japan surrendered in World War II, the allies viewed Korea’s status almost as an afterthought. Moscow and Washington split the Korean peninsula into occupation zones divided by the 38th Parallel. Two separate nations quickly evolved, threatening each other with war. But only the Soviet Union armed its protégé with heavy weapons. After securing support from Moscow and Beijing, the DPRK’s Kim Il-sung launched an invasion of the South.

The Truman administration won United Nations support, since the Soviets were then boycotting the Security Council—to protest the continued membership of Chiang Kai-shek’s government—and rushed U.S. troops to the ROK’s rescue. However, as allied forces neared the Yalu River and North Korea’s complete defeat loomed, the People’s Republic of China intervened, creating what U.S. commander Douglas MacArthur called “an entirely new war.” The battle lines soon settled near the original border and a couple years of static combat ensued. An armistice was signed in July 1953.

However, American forces remained to protect a devastated country ruled by the aging, irascible, unpopular, and authoritarian Syngman Rhee. He was ousted by a popular uprising that eventually led to a military takeover and Park Chung-hee’s ascension to the presidency. In the 1960s, Park oversaw the South’s economic takeoff, during which the ROK raced past the DPRK, removing an important justification for America’s continued presence on the peninsula.

After Mao Zedong’s death in 1976, China moderated its hostility toward Washington. Democracy came to South Korea in 1987. The Cold War ended as the 1980s closed; the Soviet Union formally dissolved in 1991, after which Russia, and then China, recognized Seoul. The case for a continuing American military presence on the peninsula dissipated, but Washington kept its forces in the ROK to advance its status as the world’s “unipower.”

Today America’s presence looks ever more anachronistic. South Korea enjoys more than 50 times the GDP and has twice the population of North Korea. The South has one of the world’s largest economies and is known for its technological prowess. It is internationally engaged and respected. So why can’t it defend itself from the impoverished, backward, and isolated North?

Of course, many South Koreans want to keep their defense subsidy. Being protected by the world’s sole superpower has obvious advantages. However, there are costs as well for the South: Washington does not treat its allies as equals, only as minor partners. The U.S. often finds it difficult to take no for an answer. Still, at only a modest sacrifice of its sovereignty, Seoul spent less on the military and devoted more to economic development, which proved highly profitable over the years.

America’s interest in turning the ROK into a defense dependent is less clear. Members of Washington’s foreign policy elite generally believe the U.S. should run the international system. Infantilizing allies enhances Washington’s dominance even while increasing the costs and risks faced by Americans, especially those serving in the military. Those who extoll the U.S.-South Korea alliance celebrate a system in which Washington, not Seoul, takes the lead in dealing with North Korea, decides on sending “the armada,” as President Trump called it, off the North’s coast, chooses to ban commerce with Pyongyang, and maintains operational control of the South Korean military in wartime.

And Washington, not Seoul, decides when South Korea will go to war to support other American objectives. At least, Washington imagines that it gets to make that decision. Only here is the alliance perhaps ready to break down. Americans routinely speak of the relationship having dual uses. That is, it defends against the North and other regional threats, which in practice means containing China.

However, South Korean officials seem unlikely to allow the U.S. to drag their nation into a war with China, turning it into a military target of a country with a very long memory, to back American objectives of little if any importance to the ROK. Which means anything other than defense of the South from a North Korean or Chinese attack.

Seoul has long been wary of U.S. aggressiveness. President Kim Young-sam claimed to have blocked Clinton administration plans to attack the North’s nuclear facilities. Roh Moo-hyun publicly insisted that his government’s approval was necessary for Washington to employ facilities in the South. Even a future conservative South Korean administration is unlikely to allow the U.S. to use ROK bases in a conflict with China over Taiwan or other East Asia-Pacific contingencies.

If not, then Washington is defending South Korea for nothing.

Some Americans imagine the military cost to be negligible, since Seoul contributes toward American basing costs. That issue, of course, is currently tied up in a bitter dispute over the so-called Special Measures Agreement. However, the main expense of the Korean commitment is not deploying units in the ROK but raising additional units for use to defend the South if necessary. Every additional security guarantee requires a larger military. Adding permanent force structure—men and materiel—is not cheap. If Washington didn’t promise to protect much of the known world in both Asia and Europe, it could rely on a much smaller military to protect America.

The U.S. is blessed with oceans east and west and pacific neighbors north and south. America’s missiles, navy, and air force ensure that no other nation can reach the U.S. without facing devastating retaliation. In fact, deterrence is relatively cheap. Power projection is far more costly. For this reason the bulk of the Pentagon’s efforts perversely are devoted to protecting other nations not essential to U.S. security, such as South Korea.

The ROK mattered during the Cold War: America faced a hegemonic threat, the Soviet Union, for a time allied with the newly created PRC. With a global contest for influence, even smaller conflicts could have outsize consequences.

That was then, however. Today the Korean peninsula has no particular security significance for America: a war would be disruptive and destabilizing, but of far greater concern to surrounding states. It would be a humanitarian tragedy, but not that much different than terrible conflicts involving the Democratic Republic of Congo, Rwanda, Liberia, Syria, and Sudan in recent decades. In none of them did Washington see any reason to intervene militarily. Most important, the ROK is well able to defend itself. Whatever its importance, there is no need for Washington to protect the South.

That was the case even before the North began developing nuclear weapons. Today Pyongyang is commonly estimated to possess 20 to 30 nuclear weapons and enough fissile material to make another 20 to 30 bombs. The DPRK almost certainly could hit American units stationed in South Korea and throughout the region, including on Guam and Okinawa. North Korea also has been developing ICBMs capable of targeting cities in the continental U.S. If it is successful, America’s defense commitment to the ROK will become prohibitively expensive. For nothing at stake in Korea is worth risking one or several U.S. cities.

And they would be in danger even in an initially conventional conflict. In 1950 American and South Korean units pursued the broken North Korean military toward the Yalu river, the border with China. Defeat seemed imminent, at which point the PRC intervened. Today Beijing almost certainly would not save the Kim dynasty. However, if faced with defeat Pyongyang would have an incentive to threaten nuclear war unless Washington pulled back. Of course, America could respond with ruinous retaliation. But since conventional defeat also would mean the end of the regime, it would have little to lose. A credible threat of nuclear war could save the regime without triggering nuclear war.

Which necessitates that the U.S. avoid involvement in any future Korean conflict. The South should develop a conventional deterrent capability and consider creating its own nuclear arsenal. The Park government began researching nuclear weapons in the 1960s, before abandoning the program under pressure from Washington. However, this time the U.S. should leave the decision with Seoul. Proliferation is not a good solution, but it still might be the best option. And it would offer another important benefit: helping to restrain China as well. Surely an independent ROK nuclear deterrent is better than having Americans promising to risk nuclear war on South Korea’s behalf.

The Korean War was a tragedy but perhaps an inevitable outgrowth of the Cold War. Today the ROK has won the competition between the two Korean states. Threats remain, but ones which Seoul is able to confront.

Washington should mark the anniversary of the Korean War by opening discussions with the South over returning defense responsibility to South Korea. America’s defense commitment is an anachronism. Equally important, the U.S. faces extraordinary challenges at home: it is time for Washington policymakers to focus attention and resources on meeting Americans’ needs.

Doug Bandow is a senior fellow at the Cato Institute. A former special assistant to President Ronald Reagan, he is author of several books, including Tripwire: Korea and U.S. Foreign Policy in a Changed World and co-author of The Korean Conundrum: America’s Troubled Relations with North and South Korea.