Started in 1949 a follow up to the North American Alliance it was based off the fear of Russia attacking Europe. This has been a perfect way to sell military arms to all these countries you cannot be a member unless you buy arms. Dwight David "Ike" Eisenhower told everyone to beware of the danger of the military industrial associates. Deep state money is behind it. When Trump left to have a meeting in the NATO the government behind his back made a commitment to back the NATO 100% to stop him from destroying it. Deep state working hard but he turned the tables on them he made it stronger putting pressure on the countries to pay their part and exposing they say they want protecting from Russia but funding it at the same time. Now Trump goes to Russia and the deep state goes crazy calling this treason relating to the holocaust why if you do not have an enemy you do not need protection. No Russia no NATO. How do you destroy NATO take away Russia as an enemy? That is why the deep state is going crazy
There is some sense to that, though. Given that NATO is a military alliance, you would want your allies to have military force. Otherwise, they are more like cheerleaders.
I listened to an interview with a former high-ranking "employee" of NATO. He essentially said that NATO was the way the U.S. found to occupy Europe without embarrassing the Europeans. It began under the auspices of a military alliance against the USSR, but it fact it was never really that. When NATO was formed (according to this guy) the members of NATO other than the U.S. and perhaps Canada could contribute very little in their own defense as they were devastated by the war. This led to the idea that the NATO could be formed, boosting European egos and at the same time serving as an excuse to occupy Europe and prevent them from destroying themselves once again as soon as they had accumulated enough military power to attack one another again. Also, as @Martin Alonzo has said above, it gave the industrialists a chance to profit from arms sales to the "Allies". Europe is lucky that Roosevelt didn't live to the end of the war, for he would have handed all of Europe over to Stalin, as he was a great admirer of the Soviets and how they did things. Truman and Eisenhower were anti-Communists, but couldn't completely reverse the advance of Soviet Communism after the agreements made near the end of WWII.
Why would there be talk of an "occupation" ? Wasn't it rather a liberation? Is there any evidence that Roosevelt would really have done that or is it interpretation? When talking about the difference between Roosevelt and Truman/Eisenhower we shouldn't forget the time aspect. It's true that Roosevelt concede that he may have been too optimistic about Stalin's real intentions and character but when it came to the crunch in spring 1945 (Polish question) Roosevelt insisted on the Jalta agreements to be kept to. He did not want to hand over all of Europe to the Soviets but at that time, with Hitler not finally beaten, he did not want to risk the coalition against him either by alienating Stalin. Once the claims were staked and the war really over, it was not only easier for Truman and Eisenhower to put their foot down but it was necessary.
In a biography of Truman, the biographer noted that Harry wanted to undo some of the agreements that Roosevelt had put in place at Yalta. Roosevelt was either envious of Stalin or he was terribly naïve about Soviet intentions. https://www.hoover.org/research/roosevelts-failure-yalta
I think he was and, at the same time, it was him, and not those succeeding him, who also had to take Soviet security needs into account at the time when the deal was being negotiated.