The foreign relations of Ireland are substantially influenced by its membership of the European Union, although bilateral relations with the United States and United Kingdom are also important to the state. It is one of the group of smaller nations in the EU and has traditionally followed a non-aligned foreign policy. Ireland has historically tended towards independence in foreign military policy, thus it is not a member of the North Atlantic Treaty Organisation and has a longstanding policy of military neutrality.

Ireland is one of four members of the European Union that are not members of NATO. The others are Austria, Cyprus and Malta. The country has a longstanding policy of military neutrality: it does not join military alliances or defence pacts, or take part in international conflicts. The nature of Irish neutrality has varied over time. Ireland declared itself a neutral state during the Second World War, and during the Cold War it did not join NATO nor the Non-Aligned Movement. Since the 1970s, some have defined it more broadly to include a commitment to "United Nations peacekeeping, human rights and disarmament". Recent Irish governments have defined it narrowly as non-membership of military defensive alliances. 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". The Irish Defence Forces have been involved in many UN peacekeeping missions.