If I’m Trump I bump that requirement up to 5%.
2 % of ALL NATO countries is a lot.
It means we can finally withdraw from the NATO treaty. And, bring all persons and assets/costs home.
They'd just laugh at it, or worse, agree and then not perform as they have up to now. Our spending is 3.57% of GDP. But even at the 2% they pledged only five nations have lived up to it: the U.S, Greece, the UK, Estonia, and Poland.
The problem is that your 5% might not actually be a bad number - defense investment won't happen in a single year, and it will take several above that target to make up for the neglect of years past. Short of an extant external threat I don't see it happening. I do see an increase in the U.S. withdrawal that's been going on for years now. Bitburg closed down last year and Ramstein can't be far off. And moving assets to Poland from Germany turns out to be the easiest and cheapest move to make.
We simply have a fundamental disagreement with our erstwhile allies as to the proper and necessary rate of defense spending, and that's fine - perhaps they won't need defense against external threats (that has, historically, been a disastrous bet to make) and stubbornly refuse to recognize the internal threat they're merrily importing. So they learn the hard way. Not our problem anymore.