Averting Nuclear Proliferation by U.S. Allies

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At the five-year review conference of the Nuclear Non-Proliferation Treaty (NPT) opening on April 27, criticism will be heard that more NATO allies may seek their own nuclear arsenals. A key reason is that doubts have grown about the U.S. “nuclear umbrella” to protect them. The U.S. might reinvigorate it through bolder steps.

Several U.S. policies since the end of the Cold War have allied caused unease. In the 1990s, the U.S. removed nuclear weapons from South Korea and never returned them even as North Korea’s became a dangerous nuclear risk and developed long-range missiles. Despite Russia’s aggression in Ukraine, irresponsible nuclear threats, and insertion of nuclear weapons into Belarus, NATO’s nuclear posture has failed to adjust.

Other U.S. actions have weakened allied confidence. The U.S. has threatened to seize Greenland from Denmark. Washington suggests it might pull troops out of Europe or not defend allies that spend too little on defense. U.S. leaders have more fractious relations with European counterparts than in the past. The recent shift from East Asia to the Middle East of warships and troops, and part of a THAAD missile defense battery from South Korea, has caused unease among allies worried about China.

The U.S. does take regional nuclear deterrence seriously. As part of NATO’s nuclear sharing program, about 100 U.S. tactical nuclear bombs are deployed in five European countries. In wartime, allied aircraft would deliver the weapons. A limited number of Trident submarine ballistic missiles now have low yield warheads. They are suited for regional deterrence, as would be a new, nuclear-armed sea-launched cruise missile that Congress is funding. Finally, the U.S. and South Korea have intensified their nuclear dialogue.

All this is important, but it may not be enough. Aircraft carrying nuclear bombs could face some of the world’s most advanced air defenses in Russia. Being largely invisible, sea-based nuclear forces may have less deterrent value than land-based ones.

Some allies are turning to Britain and France for greater nuclear cooperation. Last Month, French President Emmanuel Macron said eight allies – the UK, Germany, Poland, the Netherlands, Belgium, Greece, Sweden, and Denmark – would participate in his country’s new “forward deterrence” strategy. Some might temporarily host French nuclear bombers, offering more basing diversity. German conventional forces may participate in French nuclear exercises.

While important, this cooperation is less than the U.S. has long promised in its nuclear umbrella. French cooperation will not involve a security guarantee. Unlike the UK, France continues not to participate in NATO’s Nuclear Planning Group in which allies together address nuclear policy issues.

A few U.S. allies are discussing whether to acquire their own nuclear arsenals. Polish leaders speak of this option. Foreign Minister Hakan Fidan has raised this idea for Turkey. Three-quarters of South Koreans favor having their own nuclear arms.

Such moves could jeopardize the global nonproliferation order to which the West has long attached high priority. When the Soviet Union collapsed in 1991, the West worked hard to avert proliferation in Belarus, Kazakhstan, and Ukraine. Each inherited Soviet nuclear-armed long-range missiles and, responsibly, gave them up.

The U.S. ought to avert proliferation risks by strengthening the nuclear umbrella. It could send more nuclear bombs to Europe and base them in Poland, which its president has urged. The U.S. might increase military cooperation with Turkey, bringing it back into the F-35 fighter aircraft program. Washington could return tactical nuclear weapons to South Korea, which two-thirds of its citizens favor. The U.S. might field new regional nuclear forces, such as land-based missiles.

These steps to reduce the risk of proliferation could be negated, however, if a short-sighted U.S. were to lessen its commitment to the defense of allies. A diminished U.S. role in NATO or an unreciprocated charm offensive with North Korea could spur proliferation and put security at risk.

William Courtney was deputy negotiator in U.S.-Soviet Defense and Space Talks (missile defense), U.S. commissioner to the U.S.-Soviet Commission to implement the Threshold Test Ban Treaty, and ambassador to Kazakhstan and Georgi