A lot of this is tied to non proliferation. We'll carry the buck if you don't aquire nukes. So it's not as simple as who pays how much.

NATO members have always been supposed to spend at least 2% of GDP on military, other than the US and I think the UK literally no one was.

France does. Not surprising though, maintaining nukes and nuclear missile submarines ain't cheap.

I believe that was a goal for a future date that has not yet arrived. Trump complained about it, but it wasn't due yet and was going to happen anyway. So it can look like he made it happen. He's full of cons.

The 2% commitment was originally agreed to in 2006. After member nations continued to fail to spend enough, in 2014 it was a set as a goal to increase towards that goal year over year until 2024:

https://www.nato.int/cps/en/natohq/topics_67655.htm#:~:text=....

Several countries hadn't made real any moves towards reaching that goal, and even now are still falling far short (see page 3):

https://www.nato.int/nato_static_fl2014/assets/pdf/2020/10/p...

The reason why the EU can afford social programs is because the USA and NATO provide them with military defense so it doesn't come out of their military budgets. After Ukraine gets invaded they might want to build up their military again.

Welcome to World War 3. watch the FOSSIL fuel prices, ouch!