A quarter century after the Cold War ended everywhere else, North Korea is still going strong. Why, then, have the United States and South Korea been planning to weaken their military alliance through a flawed policy known as “OpCon transfer”? Bilateral negotiations in Washington this week are a good opportunity to shelve such plans indefinitely.

Observers routinely dismiss North Korea’s nuclear and missile capabilities, assessing calmly that Pyongyang is still several years away from posing a real nuclear threat. Yet unclassified evidence indicates that North Korea has likely already achieved a degree of warhead miniaturization and therefore has the ability to place nuclear weapons on at least its medium-range missiles.

North Korea’s regime has repeatedly proved willing to use military force, most recently in two 2010 attacks that killed 48 South Korean service members and two civilians. Since then Kim Jong Un has taken the helm of state and may be just as reckless as his father.

To deter this spectrum of threats, Seoul and Washington maintain one of the world’s most impressive military alliances. South Korea has more than 600,000 active-duty military personnel (almost half the U.S. total world-wide) and spends $30 billion a year on its armed forces, or about 2.5% of gross domestic product, making it one of America’s few allies to exceed 2%. South Korea has developed one of the world’s half-dozen best militaries and, in conventional terms at least, is almost surely stronger than North Korea. But North Korea now has the bomb.

Washington has pledged to defend its ally and, if war became imminent, would assume operational control (OpCon) of South Korean military forces. As commander of Combined Forces Command, the senior U.S. general in Korea would receive orders from both countries’ presidents and direct allied efforts to defend South Korea and defeat the North Korean threat.

But due to domestic politics in South Korea and some questionable policy decisions in Washington, the allies decided in 2007 to dissolve their single integrated military command and replace it with two parallel, independent commands. They originally planned to do so by 2012 but delayed until 2015. Now, as that deadline approaches, the North Korean threat isn’t abating.

Dissolving Combined Forces Command—perhaps the most interlinked military command structure ever invented—is ill-advised. The command has been built over 60 years to provide maximum allied deterrent and warfighting capabilities. U.S. and South Korean officers work hand-in-glove throughout the command. At any given echelon it is just as likely that a South Korean officer has local tactical control over a U.S. unit as the reverse.

As such, neither South Korean national pride, nor American desire for greater allied burden-sharing, need cause a change.

Unity of command and control is an incontrovertible and timeless feature of smart military planning. Since Operation Desert One in 1980, when three U.S. military services shared responsibility for preparing and executing the failed rescue of U.S. hostages in Iran, the U.S. government has recognized how important it is to ensure unity of command even among the U.S. Army, Navy, Air Force and Marine Corps. Desert One and other debacles led to the Goldwater-Nichols reforms of 1986, which strengthened the role of regional commanders in American warfighting and created the Special Operations Command that has so distinguished itself ever since.

Yet existing U.S.-South Korean plans would discard this principle. The current OpCon plan doesn’t so much transfer wartime operational control of South Korean forces as divide it—and in the narrow geographic confines of the Korean peninsula, where the greater range, accuracy and lethality of modern weapons make it hard to subdivide the battlefield into separate sectors.

Beyond violating military common sense, the plan has led South Koreans to waste money on duplicating capabilities that the alliance already possessed under the old command arrangements, in anticipation of the day when they would have to take on roles that the integrated command had previously committed to carry out. None of this has reduced the core demands on U.S. forces.

Washington and Seoul should instead focus on ensuring robust combined and integrated allied capabilities, such as integrated missile defense against an evolving and improving North Korean arsenal of ballistic and cruise missiles.

That said, South Korea should develop some command capacities. Ideally Seoul would ultimately take responsibility for stabilizing the territory now ruled by North Korea in the latter stages of any major war, should such a horror ever occur. In other words, at some point during a military mission, command should shift from the American general who now sits atop the military hierarchy to the four-star South Korean who is his deputy. This change makes sense because South Korea would clearly be the main actor in stabilizing a reunified peninsula.

Someday down the road—when, one hopes, the situation in North Korea would have changed—all OpCon issues could be revisited. But for the foreseeable future, defense planners in Washington and Seoul should abide by the old adage that if it ain’t broke, don’t fix it.

Editor's Note: Michael O'Hanlon co-authored this commentary.

 - Mr. Klingner is senior research fellow at the Heritage Foundation.

 - Mr. O’Hanlon is senior fellow and director of foreign policy research at the Brookings Institution.