With defence remaining an exclusive competence of Member States (MS) (Article 4§2 TEU), it is automatically excluded from the scope of European Union (EU)’s regulation. This exclusion equally applies to EU environmental regulation tackling climate change and targeting carbon neutrality by 2050. Despite not being covered by the EU's environmental regulations, the defence sector remains responsible for a large part of GHG (greenhouse gas) emissions and should not be exempt from the EU’s climate agenda due to treaty-based principles. Establishing this responsibility is possible through alignment with existing EU green legislation. The EU can offer relevant instruments to enable the defence sector to better incorporate environmental considerations in alignment with the EU green agenda, for example through procurement regulations. However, further effort should be undertaken to reach a consistent and coherent alignment of MS to that end.