Biden administration officials trekked to Seoul in late May to discuss a path toward a new “Special Measures Agreement” (SMA) that will define the parameters of military cooperation between the U.S. and South Korea for years to come.

The talks, said the U.S. embassy, “underline the enduring vitality of the U.S.-ROK alliance, which remains the linchpin of peace, security, and prosperity for Northeast Asia, the broader Indo-Pacific, and beyond.” The South Koreans have a more practical goal of holding down costs, taking “the position that our defense burden sharing will come at a reasonable level to ensure conditions for a stable stationing of” U.S. troops.

The U.S. presidential election is still more than five months away, but Washington officials and their foreign friends are already preparing for the possible victory of former President Donald Trump. Their goal is to lock in what amount to “America last” policies that Trump is most likely to challenge.

So it is with those devoted to the U.S. alliance with the Republic of Korea. Then-President Trump’s policies and rhetoric caused much distress in Seoul and resulted in an impasse over cost sharing. South Korean officials welcomed the return of the status quo after Trump’s defeat, with the Biden administration allowing the ROK’s cheap ride to continue.

However, South Korea now faces the possibility of Trump’s return. At best, it would mean a repeat of his insistence that South Koreans pay more for America’s protection. At worst, it would mean a withdrawal of U.S. forces. The result has been much wailing and gnashing of teeth in both capitals.

In response, the Biden administration has accelerated negotiations over the next SMA. The new accord won’t take effect until 2026 but would bind the incoming administration. The State Department claimed to have disinterested motives, but it’s hard to ignore the fact that concluding the deal before the next president is inaugurated would deny Trump the opportunity to set policy.

Unsurprisingly, the talks have reportedly been going well, since both sides have an incentive to finish before the campaign heats up. Today, South Koreans pay about $1.2 billion annually to underwrite the U.S. military presence. The two governments are likely to set a small increase in the ROK’s payment.

Some alliance advocates argue that Washington is getting a good deal. For instance, Troy University’s Dan Pinkston cited “the amount that Korea contributes by paying for all the electricity used by US forces here, the land used for military drills, the salaries of civilian workers on the bases and so on.” As a result, Pinkston contended “that it is actually cheaper for the US to have these troops based here in Korea than to ship them back to the US.”

Pinkston also pointed to “the intangibles at the heart of the alliance that benefited the US, such as support from Korea in cyber warfare, anti-piracy operations around the world, counter-terrorism campaigns, support for Washington in the UN and others.”

In reality, the arrangement is a sweet deal for South Korea by any measure. In exchange for a billion dollars and change — 90% of which is spent in the ROK — Seoul gets a guarantee that the world’s superpower will use military force, including nuclear weapons, to protect it from any and all enemies.

South Korean payments are not a contribution to the U.S., which is maintaining its garrison for the South’s benefit. American forces act as a tripwire to ensure that Washington political leaders have no practical choice but to go to war for the ROK, irrespective of America’s interests. The troops perform no other effective role, certainly not in confronting China, the most obvious East Asian challenge for U.S. influence.

Moreover, contrary to Pinkston’s view, South Korea does not offer a cheap location for U.S. military personnel. Force structure does not exist for its own sake but is based on security commitments. If Washington cuts its support for Seoul, it should eliminate corresponding units, personnel, and hardware rather than relocate them.

Nor does the alliance as such offer extra benefits for Americans. Washington is defending the ROK; Seoul is not defending the U.S. Moreover, Washington and Seoul can work together on other issues of mutual interest even without an American security guarantee.

Nevertheless, the Biden administration appears determined to prevent any debate over Washington’s commitment to South Korea. However, Trump could thwart this expensive cooperation by moving beyond host nation support and reconsidering America’s force presence altogether.

There are a range of good reasons to consider such a move. For one, the alliance’s costs and risks are growing. The Korean war was terrible, but American liability was limited to the battlefield. Washington fought ferociously without risking the homeland.

That would no longer be the case today. In years past, the Democratic People’s Republic of Korea hoped that its conventional threat to Seoul, which sits uncomfortably close to the border, offered sufficient deterrent to allied military action, including preventive U.S. strikes. Now, Pyongang possesses a nuclear arsenal expanding in size and a missile force increasing in range. The Asan Institute and Rand Corporation warned that, in a few years, “North Korea could have 200 nuclear weapons and several dozen intercontinental ballistic missiles (ICBMs) and hundreds of theater missiles for delivering the nuclear weapons.”

Although a preemptive attack from the DPRK would be suicidal, Pyongyang is likely more interested in deterring U.S. involvement in a Korean conflict. Should war occur, would a U.S. president be prepared to risk one or more American cities in defense of the South? Should a US president do so?

Such a conflict would be a human tragedy. The ROK is a worthy friend and ties between the American and South Korean people—family, cultural, economic, and more—are strong. Nevertheless, such interests do not warrant risking America’s very survival.

In reality, the South is capable of defending itself. Trump sensibly asked: “They’re a very wealthy country, so why wouldn’t they want to pay?” In 1953, South Korea was an economic wreck, its people impoverished and its politics authoritarian. Absent American support, the North’s Kim Il-Sung probably would have absorbed the South. However, the ROK soon began to race past the DPRK economically. Two decades later, Seoul embraced democracy, and it has now achieved a major international presence.

Although the ROK’s military has lagged behind the country’s resources, the force is capable. One U.S. military official traveling to the ROK described the latter’s military “as among the best in the world.”

“From a person who has worked with a lot of different countries, I put them at the high-end of capability,” the official said — not as “an absolute replacement for a U.S. capability, but combined it is very strong.” And that is without them seeking to replace U.S. forces. (Ironically, some South Koreans worry more about losing American money than troops, fearing fewer sales and jobs.)

The prospect of a U.S. withdrawal is not without concerns. A transfer of defense responsibility raises the possibility that South Korea could seek nuclear weapons as a deterrent against the North. The thought horrifies the usual suspects and has led U.S. policy makers to work desperately to convince South Koreans that US “extended deterrence” remains strong.

That was reflected in last year’s so-called Washington Declaration, which assumed Washington would continue to risk the destruction of American cities and slaughter of American people to protect the South. Even if South Koreans believe that Americans would do so, why should we? An ROK bomb might not be a good solution, but it might be the best among several bad options.

The SMA negotiations pale in importance compared to such issues. Why should Washington risk its people’s future to protect a nation capable of handling its own defense, irrespective of the price the latter is willing to pay? American personnel should not be rented out to even the best of friends, especially when the U.S. has no vital interests at stake.

Instead of arguing about host nation payments, the two governments should refashion the relationship and limit America’s role. The current treaty should become a blueprint for mutual cooperation. Then the U.S. troop presence should be phased out, thus terminating host nation support after the withdrawal is complete.