Were you aware !
I can't believe I'm defending Trump, but Trump to some degree said the quiet part out loud, and once in a while that's useful. Especially because a lot of people were muttering the quiet part behind the scenes.
Trump made threats to that effect during his time and it shook the whole organization. Later the US had to emphasize their respect for the treaty.
This can only go on so long, and only makes so much sense for the Americans. NATO is really the Americans (and to a lesser extent the UK and France) shielding the rest of us. That only works if we keep in their interests, and that's easier for some countries than others. To some degree we needed to be shaken to the core so we start taking this seriously.
Some of us in NATO aren't pulling our weight (see: Canada, Netherlands, Spain, Belgium and many others) but we get all of the benefits. We've agreed to 2% of GDP defence spending, including I think it's 0.4% of GDP on equipment (by 2024) - now there a lot of complexities in how to count that - but several of us don't do it. Yet if we get attacked we can invoke article 5, we get defence contracts, we get shared access to facilities etc. If we're going to have agreements we need a mechanism to make countries honour those, or the agreements are meaningless. We probably need to agree on a common counting framework (are veterans defence spending?, what about big purchases that happen infrequently?)
There are also several countries in NATO (Latvia, Lithuania, Estonia) who are small, and that are potential sources of conflict where, I hate to say it, but how big of a war do we risk over 1.2 million people who live in Estonia? What do we get out of having them in the alliance? When Clinton allowed the addition of several former Soviet bloc countries there's was very little risk reward calculation happening. NATO is a big happy family, why not let freedom loving peoples in? Hell, why not offer Russia membership in NATO if they're democratic? Putting NATO right into territory the Russians historically consider theirs was a big risk, just as something like offering admission to Ukraine would be. The MAD theory of foreign affairs, and that if we just add someone to NATO and the Russians would never risk a confrontation is a brazenly risky one, and might impel the Russians to act before that could happen again, especially in Ukraine. Russia may begrudgingly accept NATO control over the Baltics and the 6 million or so people in Latvia, Lithuania and Estonia, but letting 44 million people in Ukraine fall to NATO that's something Putin and Russia are not going to want to see happen.
We've now also got internal problems with places like Turkey and Hungary, who may have strategic assets (well, locations) of value, and Turkey particularly has a large army, but their governments are no longer the free democracies we are trying to support. How far does the alliance go for them (including things like F35's, stealth warship, future drone or night vision or telecoms tech) when they're suspiciously close with the Russians? If we're cutting them out of integrated defence equipment, planning etc. how much are they really in the alliance?
Trump was completely incapable of even understanding what defence spending as a percentage of GDP is, so I'm not saying he had any great insight here, and his efforts may have been little more than Russian efforts to undermine the alliance. But we should take seriously the idea that a 'mutual and absolute duty' only works if we're all doing our part.
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