北约协议中有一条说成员国需要出GDP的2% 的费用

Member states have thus agreed to spend at least 2% of GDP on their own militaries. The commitment is tied to NATO's Article 5, which specifies that any attack on any of the member countries is effectively an attack against them all.

https://www.msn.com/en-us/news/world/only-35-of-nato-countries-meet-the-group-s-defense-spending-target/ar-BB1iaMDG