Ireland has been neutral in international relations since the 1930s. The nature of Irish neutrality has varied over time, and has been contested since the 1970s. Historically, the state was a "non-belligerent" in the Second World War (see Irish neutrality during World War II) and has never joined NATO, although during the Cold War it was anti-communist and aloof from the Non-Aligned Movement. The compatibility of neutrality with Ireland's membership of the European Union has been a point of debate in EU treaty referendum campaigns since the 1990s. The Seville Declarations on the Treaty of Nice acknowledge Ireland's "traditional policy of military neutrality", reflecting the narrow formulation of successive Irish governments. Others define Irish neutrality more broadly, as having "a strong normative focus, with a commitment to development, United Nations peacekeeping, human rights and disarmament". Ireland's concept of neutrality There are notable differences between Irish neutrality and “traditional” types of neutral states: Traditionally, neutral states maintain strong defence forces; Ireland has a relatively small defence force of approximately 10,500 personnel. Traditionally, neutral states do not allow any foreign military within their territory; Ireland has a long history of allowing military aircraft of various nations to refuel at Shannon Airport. Under the Air Navigation (Foreign Military Aircraft) Order, 1952, the Minister for Foreign Affairs, exceptionally, could grant permission to foreign military aircraft to overfly or land in the state. Confirmation was required that the aircraft in question be unarmed, carry no arms, ammunition or explosives and that the flights in question would not form part of military exercises or operations. After the September 11 attacks, these conditions were "waived in respect of aircraft operating in pursuit of the implementation of the United Nations Security Council Resolution 1368". Irish governments have always said that allowing aircraft to use Irish soil does not constitute participation in any particular conflict and is compatible with a neutral stance, instancing the transit of German troops between Finland and Norway through neutral Swedish territory during World War II. A neutral state may also allow its citizens to serve in the armed forces of other, possibly belligerent, nations. Ireland does not restrict its citizens from serving in foreign armies, and significant numbers of Irish citizens serve or have served in the British, and to a lesser extent United States armies and the French Foreign Legion. Legal status Ireland's neutrality is in general a matter of government policy rather