The US on Wednesday pledged more troops, warplanes and warships for Europe as NATO launched its biggest military expansion since the Cold War in response to Russia’s invasion of Ukraine. The Western military alliance declared Russia the “most significant and direct threat” to peace and security, and vowed to increase supplies of arms and ammunition to Kyiv. But it is on NATO’s eastern borders that the consequences of the alliance’s summit in Madrid will be most obvious, with the creation of a major new military base in Poland.