In response to David Kurten: May, the military and the greatest betrayal in history, D. A. Christianson wrote:

‘ . . . and it could jeopardise and conflict with our membership of the far more important “Five Eyes” security and intelligence alliance with the USA, Canada, Australia and New Zealand.’

Worse, it will likely end US participation in NATO as well. Americans tend to consider Britain as friends and allies, but continental Europe as a bunch of troublemakers (with some exceptions, mostly in Visegrad). My read is this: We are quite willing to defend Britain, our friend and a true ally, and by extension NATO, but the EU, dominated as it is by Germany and France, is a completely different kettle of fish. And we have plenty of other fish to fry, with or without the UK. And those other allies include the Commonwealth your government is abandoning. Remember China is the main problem, not Russia.