The Democratic People’s Republic of Korea is angry with the U.S., citing all manner of crimes and misdemeanors. Worse, Washington has turned the Republic of Korea into an international welfare queen, apparently forever stuck on the U.S. defense dole.

It’s time for the ROK to graduate and America to allow the Koreans solve their own problems.

Last week North Korea’s deputy UN ambassador, Ri Tong-il, denounced Washington: U.S. behavior “is reminding us of the historical lasting symptoms of a mentally retarded patient.” The DPRK’s list of grievances was long.

Although it’s tempting to dismiss Ambassador Ri’s dyspeptic remarks, he made a legitimate point when justifying his nation’s nuclear program: “No country in the world has been living like the DPRK, under serious threats to its existence, sovereignty, survival.” Even paranoids have enemies.

In any war the North would face South Korea, which has vastly outstripped Pyongyang, and the U.S., the globe’s superpower. East Asia is filled with additional American allies, while the North’s Cold War partners, Moscow and Beijing, have drifted away. Impoverished, bankrupt, and alone in a world in which Washington bombs and invades small countries at will, the DPRK would be foolish to entrust its survival to U.S. self-restraint.

Which raises the question: just what is America doing with troops on the Korean peninsula?

The region never was a vital interest for Washington. At the end of World War II the U.S. and Soviet Union divided the peninsula. The North’s invasion of the ROK in June 1950 drew America back in militarily. Washington later initiated a “Mutual” Defense Treaty with the South and retained a sizable military garrison, since whittled down to 28,500.

However, South Korea began its economic take off in the 1960s. Democracy came to the South in the late 1980s. About the same time Beijing was reforming and the Cold War was ending, highlighted by the collapse of the Soviet Union.

Today the ROK has 40 times the GDP, twice the population, all the new technologies, the most important allies, access to international markets, and a system legitimized by elections and popular consent. Yet Seoul remains seemingly helpless, dependent on America.

Why should Washington defend the South 61 years after the Korean War ended?

The ROK is well able to construct whatever military forces are necessary for its own protection. The idea that Seoul cannot match a bankrupt, starving, and isolated nation with a fraction of South Korea’s resources is nonsense.

The DPRK’s nuclear capabilities are unclear, but American conventional forces on the peninsula play no role in preventing a nuclear strike. To the contrary, U.S. conventional deployments put Americans in harm’s way, creating nuclear hostages.

Some Americans envision U.S. bases in South Korea as “dual use,” part of a regional network to contain Beijing. However, with South Korean President Park Geun-hye and Chinese President Xi Jinping exchanging state visits, it would be foolish to expect the ROK to commit national suicide by joining an American war against China.

Unfortunately, the defense promise is expensive for Washington, which must not only risk war but also create a larger military to back the commitment. Moreover, the U.S. military presence inevitably makes America the focal point of North Korea’s antagonisms.

South Korea has achieved much internationally. But that only sets Seoul’s military dependence in starker relief. As I point out on Forbes online: “a serious nation in every other regard, the ROK is a defense welfare queen, abusing the generosity of the American people.”

U.S. troops should return home and Washington’s security guarantee should end. South Korea then would be freed of its embarrassing reliance on others for its defense.