The Cuban Missile Crisis almost caused a nuclear war, but fortunately neither the US nor the USSR actually wanted to fight one.
Lenin wanted to strengthen Russia by technologically advancing the country. He also wanted to strengthen Russia by removing it from World War 2 and further uniting the country.
Because of the 1962 Cuban Missile Crisis. Castro wanted to start nuclear war because he believed that the US would nuke him first. So Fidel wrote a letter to Nikita Sergeyevich Krushchev that basically said that if there was going to be a nuclear war, Russia should launch their missiles first. Luckily Krushchev didnt agree with him (that was the Cuban Missile crisis), and everyone thought he was insane for wanting to start nuclear war.
Russia
He hated Jews and wanted all the power for his Country
President George W. Bush announced that he wanted to begin building a missile defense shield for the United States because he might have been informed of upcoming events that were dangerous to the United States. This is purely speculation, however.
Project 'Manhattan' or to simply say, Nuclear Bombs and the US "Red Scare" in the early 1950s. from then on every country wanted nuclear weapons, And the First to acquire was the US, then Russia, then the United Kingdom, then France, then China, then India, then Pakistan, then North Korea. It is believed that Israel also has them, but they refuse to either confirm or deny. At the peak of the cold war arms race both the US and Russia had more than 10,000 strategic nuclear weapons and roughly 50,000 tactical nuclear weapons each, no other country in the world has ever had more than a few hundred total strategic and tactical nuclear weapons. As of 2014 both the US and Russia have reduced their stockpiles to about 3000 strategic nuclear weapons and zero tactical nuclear weapons (however the US maintains the parts from the dismantled 7000 strategic nuclear weapons and in an emergency could still reassemble them in a few months time into usable weapons, Russia likely has similar ability).
It purchased it from Russia in 1867 for 7.2 million dollars. This was to asist Russia because they were going bankrupt.
President Nixon's stance toward the Soviet Union in 1969 was one of diplomacy. He negotiated a missile treaty with them and to negotiate nuclear peace. He sought to end the Cold War.
He was concerned about certain other nations obtaining nuclear missiles
Hitler was a dictator, he wanted the throne to be only his. while Stalin wanted Russia to be a democratic country.
They were sad, and they wanted to take revenge on the Japanese so they used the nuclear bomb.