Answer:
The United States and the Soviet Union engaged in proxy wars with each other rather than face-to-face confrontation because a direct confrontation between these two superpowers would have likely led to a catastrophic nuclear war. The two sides had built up massive nuclear arsenals, and a direct conflict would have risked a mutually assured destruction. By fighting proxy wars in third-party countries, each side could advance its interests and ideology without directly attacking the other. This allowed the two superpowers to engage in a form of limited conflict without risking a larger war.