A potential future compatibility issue under this prohibition concerns the US B61 nuclear bombs stored in Europe. Arrangements are reportedly in place for control over the bombs to be given by the United States to the host states Belgium, Germany, Italy, and the Netherlands, for use in their aircraft. If this were to occur, the receiving state would contravene Article 1(1)(c) (and potentially also the NPT).
Belgium, Germany, Italy, and the Netherlands all have a nuclear role and retain nuclear-capable aircraft and pilots trained in the use of the weapons at the bases in question. The aircraft are sometimes referred to as ‘dual-key’, as their employment of nuclear weapons would have to be approved both by the US government and the government of the respective host state. In the case of the B61 bombs stationed at Incirlik in Turkey, however, any use of the weapons would reportedly be carried out by aircraft stationed at other bases, and it is not clear whether Turkey’s fighters maintain the capacity to drop nuclear bombs. There are ostensibly no nuclear-capable aircraft at Incirlik.
Belgium, Germany, Italy, and the Netherlands have recently, or are still, undergoing processes to procure new fighter aircraft. In October 2018, after years of debate, the Belgian government announced its decision to replace Belgium’s nuclear-capable F-16 aircraft with nuclear-capable F-35s. Germany is due to replace its fleet of Tornado fighters over the next few decades. In January 2019, the German government announced that it would pick either the Eurofighter or Boeing’s F/A-18. Sources reportedly specified that any replacement aircraft ‘must be able to carry U.S. nuclear weapons’. Italy was involved in the development of the F-35 from the mid-2000s and decided in 2012 to purchase 90 planes. The F-35s will replace Italy’s nuclear-capable Tornado fighters.
The Netherlands was also heavily involved in the development of the F-35 and decided in 2013 to buy 37 aircraft. However, a majority of Dutch MPs supported a motion in the Dutch parliament stating that the F-35s should have no nuclear role, reducing the role of nuclear weapons in the Netherlands’ military doctrine. The Dutch government decided to ignore the parliamentary vote, opting to procure nuclear-capable F-35s. In 2018, the government decided to increase the number of planes being ordered from 37 to 67. The final technical adjustments necessary to enable the F-35 to employ nuclear weapons (‘Block 4’) are expected to be implemented across the relevant host states between 2020 and 2024.