What Nuclear Weapons Sharing Trends Mean for East Asia

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What Nuclear Weapons Sharing Trends Mean for East Asia

Washington’s possible pursuit of nuclear sharing in Asia would capitalize on one of its main strategic advantages in the region: its many partners and allies.

What Nuclear Weapons Sharing Trends Mean for East Asia

U.S. Air Force F-35A Lightning II fighter aircraft, assigned to the 421st Fighter Squadron, Hill Air Force Base, Utah, arrive at Spangdahlem Air Base, Germany, June 11, 2019.

Credit: U.S. Air Force photo by Airman 1st Class Jovante Johnson)

The announcement on March 25 by President Vladimir Putin that Russian nuclear weapons would be stationed in Belarus, and that the two states would enter a nuclear sharing agreement, is a highly significant development not only for its impacts on the balance of power in Europe itself but rather for what it indicates regarding an emerging trend in nuclear proliferation. Widespread nuclear sharing today appears to be becoming increasingly likely as tensions in Europe and East Asia continue to rise, with the term referring to a concept and system created by NATO members allowing countries to host their allies’ nuclear weapons on their territory, train to use these weapons, and field suitable delivery vehicles to conduct nuclear strikes. This is done with the intention that in the case of war, nuclear warheads are transferred to the hosting countries by their allies and can be used near immediately. These highly controversial agreements, which have often been criticized for essentially turning countries into nuclear weapons states, appear likely to be more widely pursued, with the case of Belarus being perhaps the least consequential in its strategic impacts compared to other nuclear sharing arrangements thought to be under consideration today. 

Belarus formerly hosted much of the Soviet Union’s forward-deployed nuclear arsenal before the 1990s and maintained much of the related infrastructure intact. This infrastructure, and the already close and growing integration between its armed forces and those of Russia, could help facilitate the rapid implementation of a nuclear sharing arrangement. The impacts of such an agreement, however, remain very limited compared to those of similar agreements elsewhere. Belarus has no aircraft well-suited to deploying nuclear weapons. Its Su-24M strike fighters were its most modern in the Soviet era but have since been sold off to Sudan – and seen action in the Yemeni Civil War in conventional roles. With Belarus’ conventional forces being largely obsolete, only its Iskander tactical ballistic missile systems, very recently transferred from Russia, could provide effective nuclear delivery vehicles. The country’s tiny defense budget of well under $1 billion significantly constrains its ability to make serious use of a nuclear arsenal, while Russian Iskander ballistic missiles and other assets such as Su-35 fighters based in the country could provide the same and greater nuclear strike capabilities on behalf of the alliance. 

In contrast to Belarus’ limitations, however, other candidates for nuclear sharing agreements, as well as the existing nuclear sharing arrangements the United States has with NATO members Belgium, Germany, Italy, the Netherlands and Turkey, have far more serious implications. 

The often overlooked significance of existing nuclear sharing agreements in Europe was recently highlighted by the German Air Force’s procurement dilemma regarding a replacement for its Cold War era Tornado fighters, as the Eurofighter aircraft currently in production with Britain and continental partners is not capable of carrying nuclear weapons. While Germany is not a nuclear weapons state, the ability to carry out nuclear strikes is nevertheless a core mission that its air force equips and trains for and is expected to carry out in the event of war in Europe – as do the air forces of the other participants in nuclear sharing using American warheads on their territories. Accordingly, after the Boeing F-18E/F Super Hornet used primarily by the U.S. Navy was briefly considered, Berlin in early 2022 settled on acquisitions of the Lockheed Martin F-35 fifth generation stealth fighter. The F-35 is the only fighter of its generation known to be designed for nuclear strikes, with its deep weapons bays accommodating B61 nuclear bombs accordingly. These bombs can deliver payloads close to 25 times the size of the 15-kiloton payload used by the U.S. Army Air Force against Hiroshima. In contrast to Belarus’ limited nuclear delivery capabilities, the German, Belgian, Dutch and Italian F-35 fleets with advanced stealth capabilities, and sufficient range to engage targets across much of Russia and beyond, including bases in Syria, very significantly increase the alliance’s offensive nuclear potential.

While the United States may in the future explore nuclear sharing options with other NATO members, such as Poland, Russia’s options for nuclear sharing remain extremely limited due to the rapid erosion of its sphere of influence. The scarcity of military allies facing common perceived threats left Belarus as essentially the only candidate. As Western military attentions increasingly center on the Western Pacific, however, it is there rather than in Europe where new nuclear sharing arrangements could have potentially the most destabilizing consequences and potentially fuel a Cold War type division into military blocs as seen in Europe for most of the past 80 years. Some of the dangers of expanded nuclear sharing arrangements following the European precedent were highlighted in 2008 before the British House of Commons Defense Committee, as part of an assessment of the future of NATO and European defense, where it was noted at the time:

There are concerns that this arrangement undermines, and possibly contravenes, Articles I and II of the NPT. According to U.S. lawyers, the transfer of control is legal because, on the outbreak of “general war”, the NPT has failed in its purpose and can be regarded as no longer in controlling force… However, a nuclear sharing arrangement that may have had some logic in the pre-NPT and cold war world is now a source of weakening for the NPT, as it offers a rationale to other states to pursue a similar programme. NATO’s nuclear sharing programme could now be used as an excuse by China, Pakistan or any other nuclear-armed nation to establish a similar arrangement. Imagine if China were to offer such an arrangement to persuade North Korea to give up its nuclear ambitions. Or if Pakistan were to undertake nuclear sharing with Saudi Arabia or Iran.

While 15 years later many of the potential nuclear sharing possibilities highlighted in 2008 appear far less likely, the dangers the precedent set by NATO’s nuclear sharing, and now followed by Russia and Belarus, remain very significant. In particular, pursuit of nuclear sharing in Asia could be highly beneficial to U.S. interests primarily because it capitalizes on one of the country’s main strategic advantages in the region – namely its very large network of security partnerships and military bases and its wide sphere of influence. Japan, South Korea and Australia are leading potential candidates for nuclear sharing arrangements, with others in Southeast Asia such as Singapore potentially following suit. By contrast U.S. adversaries, namely China, have very limited options to deter or counter such proliferation with similar nuclear sharing agreements. With the majority of the region remaining neutral only North Korea is otherwise aligned firmly against U.S. and Western interests, but since the country is already a nuclear weapons state, and is in any case subjected to strict U.N. Security Council restrictions on any sharing of nuclear technologies, while also being highly unwilling to consider foreign bases on its territory, it is effectively ruled out. Thus much as Russia after the Cold War’s end could not respond to NATO nuclear sharing by proliferating nuclear strike capabilities among its own allies, with the collapse of the Warsaw Pact having effectively eliminated such options, for China too its lack of comparable security partnerships to those established by the U.S. around its borders limits its ability to respond. 

A leading candidate to be equipped with American nuclear weapons under a sharing agreement to strengthen Washington’s position in East Asia is Australia, with the AUKUS agreement and its facilitating of the Royal Australian Navy’s acquisitions of American nuclear powered attack submarines potentially paving the way to this. Indeed, with U.S.-Australian nuclear sharing having been frequently called for for years before AUKUS was announced, primarily to be aimed at China, it has been speculated that this has been the end goal for which AUKUS was established from the outset. Australian nuclear powered attack submarines will be able to operate for extensive periods in East Asia and could be equipped with very large arsenals of long-range nuclear-tipped cruise missiles. The focus on naval capabilities, rather than aerial ones as in European sharing agreements, would reflect the different requirements of the theater as well as the much greater distances over which a potential conflict would be fought. It also reflects the fact that, while in Europe conflict is primarily between regional powers, in East Asia the U.S. and most of its allies are external powers seeking to sustain a regional order based on projecting their dominance from outside. Nuclear submarines are ideal for strengthening collective Western capabilities against challengers to Western-led order in East Asia due to their high survivability, endurance and payload. Beyond submarines, the possibility of Australia acquiring American B-21 Raider intercontinental range strategic bombers, which would be another key asset for nuclear delivery, has been highlighted and at times strongly advocated, although it remains less likely and could be cost prohibitive depending on how the program evolves over the next decade. 

Following the announcement of the formation of AUKUS, in February 2022 former Japanese Prime Minister Abe Shinzo called for his country to consider a nuclear sharing agreement with the United States, emphasizing that nuclear weapons should no longer be a taboo subject for Tokyo. He reiterated this point the following month, which gained significant support from a number of senior Japanese lawmakers. While in power Abe had spearheaded moves to expand Japanese strike capabilities, which included placing major orders for the F-35 that will make Japan its leading foreign operator, as well as moving to acquire air launched cruise missiles capable of engaging targets across the region. Japan has since moved to make major acquisitions of Tomahawk cruise missiles which, with the third largest fleet of destroyers in the world, could transform its capabilities further still. These developments could all be key to paving the way for a nuclear sharing agreement, which would allow its F-35s and potentially its destroyer and submarine fleets to potentially carry American nuclear warheads.

As a further potential candidate, growing calls, including from senior officials in South Korea for the country to develop its own nuclear arsenal can be interpreted as a means of placing pressure on the United States to offer a nuclear sharing agreement. The U.S. has long opposed any potential nuclear ambitions by Seoul, which would seriously undermine the rationale for a continued American presence in the country as a protector and potentially make South Korea far more confident in its security independence. A nuclear sharing agreement could potentially do the opposite, however, and precipitate a return of American nuclear weapons to the peninsula seven decades after they were first deployed there in 1956. While South Korean public opinion is reportedly highly in favor of acquiring some kind of nuclear attack capability, calls for a nuclear sharing agreement specifically based on the NATO model have also been made and remain by far the most politically feasible option. Most recently on March 29 senior politician Joo Ho-young, the floor leader of the ruling People Power Party, raised such a possibility, highlighting that it was being considered preceding President Yoon Suk-yeol’s state visit to the U.S. in April.

The threat posed by nuclear sharing to the security interests of potential targets of Western military action, most notably China, was specifically drawn attention to by Chinese Ambassador Li Song at the Tenth Review Conference of the Treaty on Non-Proliferation of Nuclear Weapons in August 2022. He warned that the “clamour for nuclear sharing in the Asia-Pacific,” alongside the proliferation of nuclear attack submarines through AUKUS, was one of “two emerging issues facing the international nuclear non-proliferation regime.” As the United States continues to refocus its military attentions towards East Asia, nuclear sharing is likely to be pursued to strengthen its position, and could prove highly beneficial as the conventional balance of power becomes increasingly unfavorable to Western interests. By contrast, options for America’s potential adversaries to benefit from initiating similar arrangements in retaliation remain extremely limited. Rapid proliferation of the F-35 which can effectively serve as a short ranged nuclear bomber with both tactical and strategic sized payloads, and which has a respectable range by Western standards, has ensured that a potent asset for nuclear delivery is already in operation in very significant numbers across the region allowing nuclear sharing arrangements to materialize a serious impact much more quickly. How widely the aircraft is fielded also underlines how much wider America’s network of security partners are in facing down challengers to its regional dominance, drawing a strong contrast to China or Russia which have not proliferated any assets with remotely comparable offensive applications. The underwhelming nature of Belarus’ strike capabilities using nuclear weapons ultimately serves to highlight how limited American adversaries’ options for responses are, with this inability to respond translating into a limited ability to deter and thus providing an opening for the U.S. to push ahead with nuclear sharing.