Why did the US and USSR never declare war on one another?

Neither country wanted to engage in a nuclear war that would lead to

worldwide destruction.

Explanation:

The US and the USSR were the two global powers between the end of the World War II and the beginning of the 1990s. Each of them was the leader of a block, with the US being the leader of the democratic and capitalist world, while the USSR being the leader of the communist and command economy world.

Despite all of the tensions between the two, and often engaging in wars in other territories on opposite sides, they never engaged in a direct war with each other. They had everything they needed to do so, being heavily militarized and with an abundance of nuclear weapons, but luckily they didn't fight directly. The explantion for this is simple, they were aware that if they entered a war with each other they would destroy the whole world, so everyone would have lost and there wouldn't have been any gain from it.

the answer is a the king was elected to his position