Western European countries were under the influence of the US, recipients of the aid provided for reconstruction under the Marshall Plan, they were capitalist countries that founded and became members of the NATO (North Atlantic Treaty Organization) for their joint protection, and they were all concerned about the expansion of communism in the East.
During the Cold War, these countries constituted the Western bloc, confronted with the Easten bloc, formed by the communist countries under the influence of the URSS.