Article 5 of the 1949 North Atlantic Treaty is considered the cornerstone of the NATO Alliance, embodying its ’one for all, and all for one’ spirit. When one of the 30 (soon to be 32) NATO members falls victim to an armed attack, all other members must come to that state’s assistance. This assistance may include the use of armed force. When the treaty was negotiated, in 1948 and 1949, the western European nations favoured an article implying an automatic and unqualified commitment of the US to defend Europe.
The US, however, feared that such a strong wording would automatically engage them in European wars, something Congress did not want to accept. The negotiations ended in a compromise: the security guarantee was laid down in a formal treaty (a European demand), but embedded in an Article 5 formulation that does not imply automatic US involvement in an armed conflict (an American demand), and is strengthened by Article 11. Sixty years later, Article 42(7) was incorporated in the Treaty on European Union (TEU) as the EU’s ’mutual defence clause’, part of a cluster of articles relating to the ’progressive framing of a common Union defence policy’.
Substantial uncertainty remains over the interpretation of Article 42(7). Following its first and only
invocation in 2015, after the November terrorist attacks in Paris, debate intensified on how it works in
practice, its scope, the definitions of ’armed aggression’ and ’territory’, and which forms of aggression it
applies to (e.g. whether those include hybrid threats). Experts note that Article 42(7) ’leaves more room for interpretation than one might expect from a clause in a legally binding text’. Many experts hoped that the Strategic Compass would deliver clarification, however that did not occur. Läs artikel