NATO came into existence after the fall of the Soviet Union and the end of the Cold War. Russia is not a member of NATO neither is China.

The theory behind NATO for its members is it’s all about alliances and support against the big bad wolves. Both China and Russia have some dark history in taking over countries. Yes, the DS has been involved.

Here’s a  report from the conservative think tank Heritage about NATO.

https://www.heritage.org/defense/report/nato-the-21st-century-preparing-the-alliance-the-challenges-today-and-tomorrow