The Member States 25 March 1957, Consolidated version of the Treaty on the Functioning of the European Union#PART FIVE - EXTERNAL ACTION BY THE UNION#TITLE VII - SOLIDARITY CLAUSE#Article 222

TITLE VII SOLIDARITY CLAUSE Article 222 1. The Union and its Member States shall act jointly in a spirit of solidarity if a Member State is the object of a terrorist attack or the victim of a natural or man-made disaster.