What are NATO's defence obligations under Articles 4 and 5 of its treaty?

Denmark said on Thursday it was weighing whether to invoke Article 4 of NATO's founding treaty after drone incursions briefly ...

Poland responds to Russian drones incursion by invoking Article 4 of the NATO treaty − what happens next?

Article 4 has been invoked several times over NATO’s lifetime. It was invoked by Turkey amid concerns over cross-border terrorism as a result of the Syrian War. More recently, it was invoked by eight ...