Article 42.7 of the EU treaty

Article 42.7 of the Treaty on European Union (TEU) is the European Union's mutual-defence clause, requiring member states to "aid and assist" a fellow member "by all the means in their power" if it becomes the victim of armed aggression. It is the EU's functional equivalent of NATO's Article 5 collective-defence commitment, though without a standing military command to execute it.

The clause has been invoked only once: by France following the November 2015 Paris attacks, when Paris activated Article 42.7 to request allied assistance against the Islamic State. EU member states responded with bilateral support rather than a collective EU military operation, revealing the clause's political rather than operational character.

On 23-24 April 2026, Cypriot President Nikos Christodoulides put Article 42.7 on the agenda of the EU informal leaders' summit in Nicosia in the context of the Iran war and Hormuz shipping threats. The summit brought 26 heads of government together in the same building where the Reuters report on the Pentagon's NATO punishment email broke. Whether the Cyprus discussions produce an Article 42.7 working group on allied-flagged shipping is the live European question.