Why did us and USSR engage in arms race?

The arms race between the United States and the Soviet Union emerged during the Cold War as both superpowers sought to assert their dominance and ensure national security. Each nation aimed to develop and stockpile advanced nuclear weapons and military technology to deter the other from potential aggression. This competition was fueled by ideological differences, mutual distrust, and the desire to maintain a strategic edge in military capabilities, leading to an escalation of tensions and an ever-growing arsenal on both sides. Ultimately, the arms race became a defining feature of the Cold War era.