During his campaign, Donald J. Trump proposed to deal with the problem of North Korea by pressuring China to convince its ally to give up nuclear weapons and the missiles designed to carry them. Yet after North Korea’s recent test firing of several missiles, China proposed a solution to the problem, which the Trump administration summarily rejected.

China proposed that North Korea suspend its nuclear program in exchange for the United States and South Korea suspending their joint military exercises on the Korean peninsula, which triggered the North Korean missile tests. Although the Trump administration quickly nixed China’s idea, in consideration of its prior campaign rhetoric, the Chinese proposition should be reconsidered.

Also during the road to the White House, Trump suggested that the United States should be less active in wars overseas and thus let its allies assume more of the defense burden. China’s proposal would actually help the administration work toward that goal while making a start at getting North Korea to give up its nuclear weapons program—or at least freezing it so that the North stops obtaining more weapons.

Of course, at stake is not only the North’s nuclear weapons program but the American Empire of one-sided alliances around the world; the United States, to be the big man on campus, provides security for wealthy allies but gets little back economically from full opening of their markets to American products and services. In fact, over the decades, those allies have become rich in part by using the money they save in reduced defense spending to compete with American companies around the world. The South Korean “economic miracle” was based on physical protection by the U.S. military and trade protection against American goods and services.

Currently, this economic miracle has given South Korea the twelfth largest economy in the world, which is more than 35 times the GDP of its starving, communist North Korean enemy. Little doubt exists that South Korea could not only do more for its own defense, as Trump suggested, but defend itself without American help. Therefore, South Korea could begin spending more on defense to build up its military forces, while joint U.S.-South Korea military exercise are suspended. These joint exercises would be unneeded when, after a few years, South Korea was weened away from needing U.S. protection.

Without a U.S.-South Korea alliance on its border, North Korea might be less paranoid and therefore more susceptible to Chinese pressure over its nuclear weapons program. In addition, the Chinese would be more inclined to apply such pressure. China is not fond of having an unstable nuclear weapons state on their border. Yet at the current time, the Chinese have been reluctant to apply to much pressure on North Korea for fear the regime will collapse, create a surge of refugees into China, and ultimately lead to a unified Korea on its border protected by the powerful U.S. military (similar to the inclusion of a unified Germany into the expanded NATO alliance in Europe after the Cold War ended).

Historically, China has been sensitive to other great powers’ military activity near its borders. For example, it fought a border war with the Soviet Union in 1969, flooded troops into North Korea during the Korean War in the early 1950s when U.S. forces there got too close to the Chinese border, and helped North Vietnam against the United States in the late 1960s and early 1970s. Furthermore, legitimate Chinese aspirations to be a regional power would be given a safety valve if the United States removed the Cold War-era alliances ringing and containing China, including the one with South Korea.

In the 1800s, Britain allowed its then-adversary United States to rise as a great power, because a vast ocean between them mitigated the threat. Today, an even bigger ocean separates China and the United States. If the United States wants China to police and constrain its allies—that is, North Korea—it must be willing to give up something in return. That is, if saving money by gradually ending the protection of a rich, ungrateful South Korean ally is really giving anything up.