Dear Student,
a. The period after the Second World war is characterised by Cold war which was more of an ideological conflict between the two Superpowers , US and USSR.
b. US represented the Capitalist bloc, USSR on the other hand supported state led economy and believed in the ideology of Communism
c. The superpowers during the cold war formed military alliances to counter each other's move.
d. During the Cold war USA thus, joined NATO that is North Atlantic Treaty Organisation. It also later formed Southeast Asia Treaty Organization that is SEATO.
Regards