The Soviet Union wanted to spread its ideology of communism worldwide, which alarmed the Americans who followed democracy. The acquisition of atomic weapons by America caused fear in the Soviets. Both countries feared an attack from each other.
The Cold War Was Not A Physical War But The Americans And The soviet Union Were scared Of Each Other Attacking One Another
Soviets resented the Americans long refusal to treat the USSR as a legitimate part of the international community as well as theirdelayed entry into World War II, which resulted in the deaths of tens of millions of Russians.