The North Atlantic Treaty is signed

What happened

Twelve states sign the treaty in Washington. Three of its articles govern this module: Article 5, under which an armed attack against one is an attack against all; Article 3, which commits the parties to maintain and develop their individual and collective capacity to resist armed attack; and Article 10, under which any European state able to further the treaty's principles may be invited to accede.

Article 10 is the legal route by which the eastern flank came into existence at all — every state in this module east of Germany joined under it, in waves this timeline records. Article 3 is the clause NATO itself cites as the root of resilience and civil preparedness, and Article 5 is what the forward formations are there to make credible.

Confidence: High