West Berlin was given supplies from the Western allies (USA, Great Britain, France) in the Berlin air lift because the Soviets blockaded Berlin in the hopes of gaining control of all of Berlin and eventually all of Germany
In general, the Monroe Doctrine represent a change in President Washington's foreign policy, since the Monroe Doctrine dictated that the US would treat any further attempts by Europeans to colonize the Americas as acts of aggression, and Washington was far more isolationist.
