[Britain has foreign entanglements that force it to take Russia and China seriously as threats, plus as an island nation we depend very heavily on the sea for raw materials to fuel our economy.]
The morons running US foreign policy in the immediate postwar period pretty much forced the European colonial powers to exit their hard-won conquests around the world. We are now literally paying for it with defense budgets as a % of GDP that are quadruple what they were pre-WWII, and hit a peak of 12% during the Cold War, because two of the five permanent members of the UN, China and Russia, are the same world-conquering empires they’ve always been, whereas Britain and France are no longer pulling their military weight, since they no longer have empires to defend. Eisenhower may have been a great peacemaker as SCAEF, but his Suez decision cost US dearly and continues to cost US today.