Comments by "D. San" (@DSan-kl2yc) on "NATO makes major changes to address new threats | DW News" video.

There were two reasons. One was just for cohesion. It serves to keep cooperation and peace, and to prevent them getting invaded. Also, after the soviet's fell, Russia stopped being the enemy. That's why they've been so pleasing to Russia. They were trying to make sure Russia didn't go the route of the USSR as an enemy, or another NK, with its Nukes. They wanted an ally. Its why they got complacent. At first they thought Russia was going to become a capitalist country and that would solve it. They thought they'd follow international laws and could be talked to. They thought they could use Russia's interests and negotiate.
1