North Korea’s long-range rocket launch and the nuclear test that preceded it have sparked renewed calls from several security experts in Seoul for South Korea to acquire its own nuclear weapons. Their main argument is based on the logic of leverage: that matching the North’s arsenal would impel it to negotiate an end to these threats. Beijing would also be persuaded finally to use its own leverage over Pyongyang to compel it to stop its strategic provocations. Or so goes the reasoning.

For South Korea to seek its own nuclear weapons would be a desperate gamble, however, with hugely negative consequences for the nation’s economy, security and international status. Any debate on the subject needs to take these downsides into account.

For starters, pursuing nuclear weapons would be disastrous for South Korea’s nuclear energy industry. By law, the United States and other international partners would end all forms of civil nuclear cooperation, cutting the supply of uranium fuel to the nation’s 25 reactors. Facilities for fuel fabrication, nuclear research, medical-isotope production and other nuclear-science purposes would also be affected, putting at risk assets worth hundreds of billions of dollars.

South Korea’s $40 billion contract to construct and manage four U.S.-designed nuclear power plants in the United Arab Emirates would also be threatened. High hopes for becoming a leading nuclear technology exporter would wither.

Whether trading partners would apply other economic sanctions is hard to predict, but one might look at the measures leveled against India and Pakistan after their 1998 nuclear tests. In that case, U.S. law required the termination of nonhumanitarian assistance, defense sales and credit guarantees, as well as opposition to lending by international financial institutions. Japan froze new loans and grants to the countries. Other nations suspended aid and credit lines.

Being highly dependent on foreign trade, South Korea’s economy is vulnerable to such measures. The economic impact of even partial sanctions that reduced access to trade, finance and investment markets would be substantial. The ensuring economic impact from capital flight, postponed investment and stock market depression could be even more adverse than the direct impact of sanctions.  

Worse, going nuclear in defiance of the global nonproliferation policy would threaten an alliance that has been fundamental to South Korea’s peace and prosperity. Revocation of the U.S. deterrence commitment is not inevitable, but that is what Henry Kissinger threatened President Park Chung-hee with in 1975.

Pursuit of nuclear weapons would make South Korea intensely vulnerable in the period before the North produced and fielded deliverable nuclear weapons. North Korea might be tempted to launch a preemptive attack at a time when the U.S. defense commitment might no longer apply.

Short of this worst-case scenario, rather than negotiate disarmament, North Korea more likely would claim the South’s actions as a justification for stepping up its own nuclear program.

If South Korea were to acquire nuclear weapons and the North did not back down, under what conditions could they be given up without signaling defeat? The peninsula would be left with an enduring nuclear standoff.

Other neighboring nations would have ample reasons for viewing South Korean nuclearization with anxiety. Russia and China could be expected to target the nuclear weapon facilities. Japan could be prompted to reconsider its own weapons options, for which it would have a large head start over Seoul.

A nuclear domino effect is not certain, but it is a real possibility. The unraveling of the nonproliferation regime could see Taiwan also going nuclear. Northeast Asia would become much more tense and dangerous.

Other costs of going nuclear include damage to South Korea’s international standing as a leading global citizen. A nuclear South Korea might not be regarded as a “rogue state,” but its movement in that direction would be precipitous. The country would lose the moral high ground and would find it harder to sustain international pressure against Pyongyang. The cause of unification also would be undermined. Indeed, the political unity of South Korea itself would fray in the event of such a divisive act.

Fortunately, cooler heads can be expected to continue to prevail. Government officials in Seoul know the demerits of going nuclear and remain steadfast in support of nonproliferation. They must worry, though, about those who argue the contrary.

By Mark Fitzpatrick

Mark Fitzpatrick is the executive director of the International Institute for Strategic Studies Americas office and author of “Asia’s Latent Nuclear Powers: Japan, South Korea and Taiwan.” — Ed.