Most of the countries of Europe are members of one or more major treaty groups. The map linked above portrays these groups with a combination of colors and patterns. Great idea, although I am not sure how you read it if you happen to be colorblind. I wonder, though, if this means much of Europe has to deal with four different kinds of bureaucracy in addition to each country’s national and local systems of governance. Lots of governance, and none of it comes free!
BTW, the small dark wedge between Lithuania and Poland is part of Russia. In fact, Russia has major military installations on that part of the Baltic coast. Which is part of why Lithuania, Latvia, and Estonia may be a little nervous about Russian intentions.