U.S. President Donald Trump made headlines last October when he announced he had given South Korea approval to build nuclear-powered submarines. It’s unclear whether the United States will supply the nuclear fuel or permit South Korea to enrich its own, but the latter option would effectively give South Korea the technical capacity to produce nuclear weapons quickly—within a matter of months—if it so chooses, a condition known as nuclear latency.

To do this, Trump would theoretically need Congress to revise the bilateral U.S.-Korea nuclear cooperation agreement, known as the 123 Agreement. Last updated in 2015, this agreement allows South Korea to enrich uranium up to 20 percent and pursue pyroprocessing for civilian purposes with U.S. consent. However, it explicitly prohibits enriching or reprocessing U.S.-origin nuclear materials for military use, a category that includes fuel for nuclear-powered submarines.

U.S. President Donald Trump made headlines last October when he announced he had given South Korea approval to build nuclear-powered submarines. It’s unclear whether the United States will supply the nuclear fuel or permit South Korea to enrich its own, but the latter option would effectively give South Korea the technical capacity to produce nuclear weapons quickly—within a matter of months—if it so chooses, a condition known as nuclear latency.

To do this, Trump would theoretically need Congress to revise the bilateral U.S.-Korea nuclear cooperation agreement, known as the 123 Agreement. Last updated in 2015, this agreement allows South Korea to enrich uranium up to 20 percent and pursue pyroprocessing for civilian purposes with U.S. consent. However, it explicitly prohibits enriching or reprocessing U.S.-origin nuclear materials for military use, a category that includes fuel for nuclear-powered submarines.

But two weeks after Trump’s initial announcement, the White House released a fact sheet that laid out a way to bypass Congress altogether. “Consistent with the bilateral 123 Agreement and subject to U.S. legal requirements,” it said, “the United States supports the process that will lead to the [Republic of Korea’s] civil uranium enrichment and spent fuel reprocessing for peaceful uses.” Unlike authorizing nuclear-powered submarines, granting South Korea consent for developing those technologies for civilian purposes faces no immediate legal barriers and does not require Congressional approval.

Though plenty of uncertainties remain, if the Trump administration continues down this path, it would pave the way for South Korea’s nuclear latency. The key question, then, is whether Washington should support this development. However provocative this may sound, my answer is “yes”—not because nuclear latency comes without risk, but because all the alternatives may be even worse for U.S. interests.

Although South Korea’s acquisition of enrichment or reprocessing........

© Foreign Policy