It's important to note that the EU defense pact carries out EU-coordinated missions unrelated to NATO-style defenses. These missions are arranged by a body in which Denmark doesn't have a voice at the moment, and every country can pick and choose which missions their troops go on. The military involvement in a given mission is not forced just by being part of the pact. On the other hand, not being part of the pact excludes Denmark from any missions they might have an interest in.

Source: https://www.dr.dk/nyheder/politik/forsvarsforbeholdet-skal-t...