One of the short-lived governments of the early days of the democratic period promoted NATO accession on condition that the country remained free of nuclear weapons. The social-democratic majority government that ensued shortly after promised a referendum on continued NATO membership. While the government campaigned in favor of Spanish permanence in NATO, it insisted that Spain must remain free of nuclear weapons. The outcome of the referendum confirmed the permanence of Spain in the Atlantic Alliance, and as well as its non-nuclear condition. In 1986, Spain acceded to the Treaty on Non-Proliferation of Nuclear Weapons (NPT), which gave way to a period in which Madrid distinguished itself for its excellent non-proliferation credentials.
Treaty on the Prohibition of Nuclear Weapons: to Sign or not to Sign?
With the referendum, the issue of nuclear weapons was all but archived. It hardly re-surfaced in public debates for decades. It was only after the adoption of the Treaty on the Prohibition of Nuclear Weapons (TPNW) in 2017 that the issue of nuclear weapons returned, albeit modestly, to the political and public debate in the country.
By then, the political landscape offered a more fertile ground to opening up such discussion than in previous decades, when two large, moderate parties - centre-left Partido Socialista and centre-right Partido Popular - alternated in power, with the occasional support of nationalist parties. Indeed, foreign policy elites associated with both parties upheld adherence and support to NATO arrangements, and chose to stay away from discussions that could challenge the consensus fraught in the early 1980s. Elite consensus assumed that discussing extended nuclear deterrence risked re-opening a broader debate on the adequacy of NATO guarantees for the security of Spain, fundamental questions which have not been discussed since the early 1980s. Combined support for both parties dropped from 83.8% in 2008 to 73.4% in 2011 and 50.7% in the 2015 national elections. A party system long dominated by two big parties gave way to a number of new ones. A first stage saw the rise of a centrist party, Ciudadanos, and far left party Podemos (renamed Unidas Podemos), which accompanied the electoral success of secessionist parties in Catalonia. In a second step, a far right party, Vox, contributed to the fragmentation of the political landscape.