World After 1945 (Updated) — Social Science STD 9 — Question

During the era of 'cold war', there was struggle for supremacy between the USA and the USSR. However, the 'balance of power' was maintained by:
→ The USA and the USSR matched each other in research and development of nuclear weapons.
→ The USA and the USSR developed Inter-Continental Ballistic Missiles (ICBM). Thereby they deterred each other from the use of nuclear weapons.