In response to North Korea’s recent nuclear test, a debate has reemerged in South Korea about whether the country should deploy nuclear weapons of its own. Last week, Prime Minister Hwang Kyo-ahn declared that the government maintained its official position that South Korea would not possess or develop nuclear weapons. This is not the first time this debate has bubbled up to the surface. In November 2010, when it was revealed that North Korea had built an advanced plant for the production of highly enriched uranium (HEU, which can be used to construct a nuclear weapon), the South Korean defense minister raised the possibility of reintroducing US tactical nuclear weapons.
Some background: South Korea has a sophisticated infrastructure for the production of nuclear energy and cooperates closely with the United States on the development of its nuclear industry. South Korea did pursue a nuclear weapon of its own during the 1970s, but it abandoned the program under pressure from the United States and signed the Treaty on the Nonproliferation of Nuclear Weapons (NPT) in 1975 as a state not permitted to develop nuclear weapons. The United States stationed tactical nuclear weapons in South Korea during the Cold War, but these weapons were withdrawn in 1991, when North and South Korea signed a declaration calling for the denuclearization of the Korean peninsula. You can learn more about the history of South Korea’s nuclear programs from the Nuclear Threat Initiative.
South Korea continues to enjoy a military alliance with the United States that lends it protection under the “nuclear umbrella.” That is, the United States would respond to any nuclear attack on South Korea (presumably, one launched by North Korea) by launching a nuclear strike against the attacker. By this logic of “extended deterrence,” South Korea enjoys the protection of the American nuclear arsenal without having to acquire weapons of its own.
It will be interesting to see whether confidence in the nuclear umbrella begins to erode if and when North Korea develops a missile capable of delivering a nuclear weapon to the United States. Currently, they do not possess such a missile, and the succession of failed tests suggests that they are still a long way from such a capability. If, however, North Korea were in a position to launch a nuclear attack on the United States, then South Korea may start to wonder about the United States’ nuclear guarantee. As long as North Korea cannot hit back after a retaliatory strike by the United States (in response to the North’s nuclear attack on the South), then the United States does not have to fear for its own safety when it launches the retaliatory nuclear strike against North Korea. If, however, North Korea might be capable of launching a nuclear weapon after the United States’ retaliatory strike, then the calculation becomes quite different. South Korea may find itself wondering whether the United States would be willing to sacrifice Los Angeles to respond to an attack on Seoul. In other words, South Korea (and others) may find itself questioning the credibility of the United States’ nuclear deterrent and may start to wonder if it really does need nuclear weapons of its own.
Questions exactly like these arose among the United States’ western European allies during the Cold War, when the United States was similarly pledging to retaliate against a Soviet attack on western Europe (either conventional or nuclear, depending on the time period) with a nuclear attack on the Soviet Union. In fact, doubts about the credibility of the American deterrent helped spur France to pursue its own nuclear weapons program. Hopefully we are still a long way from the day when South Korea will find it necessary to act on similar doubts.