A referendum on the abolition of the defence opt-out, one of the country's opt-outs from the European Union, was held in Denmark on 1 June 2022. The referendum was announced on 6 March 2022 following a broad multi-party defence agreement reached during the 2022 Russian invasion of Ukraine. The referendum resulted in the "Yes" side winning with approximately two-thirds of the vote.

The European Union (EU) is a supranational political and economic union of 27 member states that are located primarily in Europe. The Union has a total area of 4,233,255 km2 (1,634,469 sq mi) and an estimated total population of over 448 million. The EU has often been described as a sui generis political entity combining the characteristics of both a federation and a confederation.