It does as part of the Lisbon Treaty, and the obligation is binding. More here: https://eur-lex.europa.eu/EN/legal-content/glossary/mutual-defence-clause.html

It does as part of the Lisbon Treaty, and the obligation is binding. More here: https://eur-lex.europa.eu/EN/legal-content/glossary/mutual-defence-clause.html https://eur-lex.europa.eu/EN/legal-content/glossary/mutual-d... And I would expect the call to be answered (with the exception of the already-compromised countries).