US President Donald Trump has been making a series of blunt statements against the transatlantic agreement, which the United States itself initiated in 1949. He is justifying his attacks on the grounds that Europeans are refusing to participate in the war he is currently losing in the Middle East. Europe now knows that it cannot count on him to come to the aid of one of its members in the event of an aggression. There is now no ambiguity: Trump's America will not come to Europe's aid. Europeans must take responsibility for the collective defence of the continent and organise a de facto solidarity amongst themselves in the event of an attack.