As South and North Korea exchanged artillery fire in late August, the U.S. rushed three B-2 bombers to Guam. The Obama administration hoped to deter the North from taking military action, but why is Seoul still a helpless dependent 62 years after the Korean War ended?

Imagine a hostile relationship existing between the U.S. and Mexico. The Mexicans threaten America with war. Washington responds by begging Europe and Japan to send military aid.

America would face raucous laughter. After all, the U.S. has more than 2.5 times Mexico’s population. America’s GDP is an even more impressive 14 times that of Mexico’s.

Yet the disparity between the ROK and Democratic People’s Republic of Korea is larger. The South enjoys a population edge of two-to-one and an economic advantage upwards of 40-to-one.

Seoul has stolen away the North’s chief military allies, China and Russia, which no longer would fight for the DPRK. On every measure of national power save military South Korea dominates. And it lags on the latter only out of choice.

ROK officials occasionally resent America’s dominant role. Nevertheless, the South, like Japan and Europe, likes having a superpower pick up a big chunk of its defense tab.

The South’s dependent relationship does not benefit America. The more defense commitments the U.S. makes, the larger the armed forces it must raise and deploy.

The principal burden is not the cost of basing troops in the South, for which Seoul helps pay, but the expense of creating the units. Today Americans must pay an exorbitant price to project power far from the U.S. even when they have no vital interests at stake.

Equally worrisome is the prospect of using those forces in a war. North Korea would lose, but the cost likely would be horrendous.

Unfortunately, the Kim dynasty has made provocation and brinkmanship the core of its foreign policy. Mistake or misjudgment could turn a violent act into a general war. Opined Defense Secretary Ashton Carter: “Korea is one of these places that is a tinder box. It’s probably the single place in the world where war could erupt at the snap of our fingers.”

Why is the U.S. still entangled in the volatile geopolitics of the Korean peninsula?

It’s certainly not because the ROK is incapable of defending itself. Some analysts imagine American forces on the peninsula doing double duty, both protecting the South and serving other U.S. interests. However, there’s no cause for garrisoning the Asian mainland.

An army division in Korea wouldn’t be much use in a war with China. Indeed, the ROK would not allow the U.S. to turn South Korea into a battlefield. South Koreans will have to live with the PRC long after America goes home.

There are areas where the U.S. and South might want to cooperate militarily, but that only requires a shared interest, not a “mutual” defense treaty. On other issues, such as economic development and environmental protection, the military relationship is irrelevant.

South Korean governments have sought to “pay” the U.S. by participating in some of Washington’s more foolish wars—Vietnam, Iraq, and Afghanistan. However, the small ROK contributions, especially in the latter two conflicts, do not warrant a permanent security guarantee and military deployment amidst the most volatile and dangerous military confrontation on earth.

Other ties, including commercial and family connections, span the Pacific. But trade and friendship do not depend on a military relationship.

What to do about the North would remain an issue, but it wouldn’t matter much to the U.S. Pyongyang is threatening to attack America only because American troops target the DPRK. North Korea’s neighbors, including China, have far more at stake in stopping the North’s nuclear activities.

As I wrote in National Interest online: “U.S. foreign policy should reflect global realities. The radical transformation of Northeast Asia over the last six decades requires a similarly radical transformation of U.S. policy.”