The US is an occupying power in Europe, not an ally! Russia has all but (Kaliningrad excepted) retreated to it's own borders and the UK has 'Brexited', the only remaining (since 1945) occupying power is of course the USA. It's totally absurd to suggest that Europe can't make it's own decisions with regards to Russia or if push came to shove could not defend itself without help from an occupying power!!!
