North Korea recognizes no limit on either the range or payload of its missiles. At the same time, the United States restricts the range and payload of South Korea’s missiles. Washington should stop weakening the Republic of Korea’s ability to defend itself.

The ROK has one of the world’s largest economies; South Korean businesses are active around the globe. Seoul is building a blue-water navy and has begun participating in international peacekeeping missions. Yet the country remains a security dependent of America.

Only in early October did Washington agree to adjust the treaty, signed in 1979 and amended in 2001, restricting South Korean missiles to a range of about 186 miles and a payload of 1,100 pounds. The ROK joined the Missile Technology Control Regime in exchange for American technical assistance.

These limits stood even as the so-called Democratic People’s Republic of Korea developed nuclear weapons and long-range missiles. Under the new accord Seoul still is barred from deploying any missiles with a range longer than roughly five hundred miles. The payload restriction on missiles also remains, though the limit was raised for drones. At least the South Koreans will be able to hit targets anywhere in the North.

Chun Yung-woo, the ROK government’s national-security adviser, explained: “The most important purpose of revising the missile guideline lies in deterring armed provocations by North Korea.” The Pentagon spokesman, Lieutenant Colonel Steven Warren, made a similar point: the “new missile guidelines are designed to improve their ability to deter and defend against DPRK ballistic missiles.” However, the South Koreans still won’t be able to defend themselves from more distant threats or employ more destructive warheads. The policy is bizarre in the extreme.

Washington has kept the ROK dependent for decades. South Korea was created by U.S. occupation authorities after World War II and gained formal independence only under American control. Washington did not trust the South’s dictatorial President Syngman Rhee and therefore refused to provide his forces with heavy weapons.

After the North Korean invasion in 1950, U.S. forces intervened and ran the war effort. Washington decided to end the conflict inconclusively, over Rhee’s objections, but retained formal control over the ROK military through the Combined Forces Command. (The latter was supposed to go to Seoul this year, but the transfer was delayed to 2015.) Later Washington forced ROK dictator Park Chung-hee, whose daughter is running for president this year, to end his nuclear-weapons program.

America’s restrictions on South Korea might have made sense when Seoul had no choice but to rely on the United States. During the 1950s, the ROK was desperately poor and politically unstable. The North was backed by both China and the Soviet Union. The South still needed Washington’s aid and could not be trusted to use its power responsibly.

But that world disappeared long ago. For some time, Seoul has lobbied to revise the missile treaty. Argued President Lee Myung-bak earlier in March: “The 300km [range] was set many years ago on the assumption fighting would happen around the demilitarized zone.” Today, however, he observed that his nation faced “new needs in its defense environment.” His government proposed to expand the missile range to one thousand kilometers and raise the payload to more than a ton, while the Pentagon opposed any increase—hence the recent compromise.

Washington should have dropped all restrictions. There is no good reason for the United States to limit the South’s ability to defend itself.

The most curious objection to relaxing the standard is that doing so will stoke an inter-Korean arms race. However, Pyongyang already is racing, with a nuclear-weapons program, an intercontinental-missiles initiative, extensive and entrenched artillery targeted on Seoul, and an oversize military spring-loaded on the border. Daniel Pinkston of the International Crisis Group warned that “anyone who thinks the North won’t respond is either naive or foolish,” but North Korea will always find a pretext for its aggressive behavior. The DPRK is more likely to respect strength in the South.

Another concern is that Seoul might use its financial wherewithal to build a superior military and attempt to liberate North Korea. Indeed, one reason Washington refused to arm the ROK before the Korean War was Syngman Rhee’s threats to march north. However, the DPRK’s ability to strike the South Korean capital is a significant deterrent, and there is no political support in the South for a reckless policy that would sacrifice the future.

Seoul is in the position of a chess player who merely needs to avoid a blunder and play out a won game to collect the point.

The third complaint is that other nations oppose any change. Shin Won-shik, a South Korean defense official, explained that the new limit was intended to avoid “unnecessary misunderstanding and friction with neighboring countries.”

In particular, Beijing opposes the ROK building missiles that might reach Chinese territory. However, potential aggressors should not be allowed to insist that their potential victims remain disarmed. Although Chinese military action against the South is highly unlikely, the best way to prevent such a contingency is to ensure that Seoul has deterrent capability against even the People’s Republic of China. That would help constrain Beijing’s ambitions without America’s direct involvement.

Anyway, China has done nothing, or at least nothing effective, to constrain the DPRK’s development of missiles or nuclear weapons, so the United States is under no obligation to restrict its ally. If Beijing wants to keep the ROK disarmed, then the former should offer something in return—such as taking effective action against the North’s weapons development. Absent that, China has nothing to say on the matter. If the PRC is bothered by the prospect of a better-armed South Korea, it should do more to prevent a better-armed North Korea.

Japan, too, may prefer that the South eschew medium-range missiles. However, the time is long past for these two democratic states to reconcile. Tokyo’s colonial misrule lies sixty-seven years in the past. The ROK and Japan have far more to fear from China than from each other.

Finally, dropping the limit would help end Seoul’s defense dependence on America. North Korea’s military provocations two years ago—sinking an ROK military vessel and bombarding an ROK island—have spurred Seoul to improve its military. Noted the International Crisis Group:

The South has been working to upgrade its military hardware to defend against DPRK provocations. It has obtained additional stealth air-to-surface missiles and advanced cluster bombs and is developing deep-penetrating ‘bunker-buster’ bombs capable of destroying fortified artillery in the event of a new shelling attack. It wants to revise an agreement with the U.S. that has limited the range of its ballistic missiles.

Daryl Kimball of the Arms Control Association complained that the ROK didn’t need longer-range missiles because “these targets in the North can already also be destroyed by the United States.” But why should the United States be expected to do what should be South Korea’s job? Some military analysts have advocated returning American tactical nuclear weapons to the ROK. Why do that when Seoul could do so much more for its own defense? The “Mutual” Defense Treaty between Washington and Seoul is archaic. The South has raced past North Korea: the former has twice the population, about forty times the GDP and a vast technological edge. The ROK no longer needs defense welfare from the United States, especially since America is effectively bankrupt. Washington needs to stop writing checks that it can’t afford to pay.

Lifting missile restrictions should be merely the first step. The United States should accelerate the transfer of operational control. The ROK should be in command of its own troops. If Seoul isn’t ready, it should get ready.

Moreover, America’s nearly thirty thousand troops should come home. The ROK can field a much larger military if it desires.

Finally, Washington should drop the misnamed Mutual Defense Treaty. Like a similar agreement with Japan (and the multilateral NATO enterprise), there is little mutuality. Washington’s job is to defend the ROK. Seoul’s job is to be defended by Washington. Although the South has provided small troop contingents in Afghanistan and Iraq, that is minimal recompense for seven decades of defending the ROK from all comers. The U.S. risks involvement in a large war with only limited interests at stake for America in return for the South occasionally dabbling in limited conflicts. This arrangement was never fair; today it is no longer necessary.

Seoul should not only do more to defend itself. It also should do more to cooperate with other nations in the region, especially Japan. Their relationship remains tainted by memories of Japan’s colonial rule as well as ongoing territorial disputes. Earlier this year, President Lee Myung-bak negotiated a modest intelligence-sharing agreement with Tokyo, which generated strong opposition criticism and foundered before being implemented. Such irresponsibility is possible only because both countries are able to rely on the United States instead of being expected to be responsible for their own defense.

Washington should not take peace for granted. Earlier this year Defense Secretary Leon Panetta said of the Korean peninsula: “We’re within an inch of war almost every day in that part of the world.” For what purpose? It’s time to get out. Eliminating restrictions on the ROK’s ability to defend itself would be a good first step.