Trump proposed NATO reassessment, i.e. Americas involvement in NATO in terms of costs and returns. Just like many issues (healthcare, trades...), this is another typical Trump-style view: always looking for better "deal", doing things "smarter" without considering their strategic or ideological aspects. In Trump's mind, if every NATO member thinks NATO is important, they should pay the cost of its being important, i.e. pay their shares of nato cost which requires 2% of GDP of each members on their military spending. For 28 NATO countries, 80% of them fail to fulfill this requirement. A few countries meet this requirement because of different reasons. France is one of largest arms exporter in the world, they profit from some of their military spending. Turkey does so because of fighting Kurd separation and its border issue with Greece.
So, now American tax payers take 75% of NATO spending. For this reason and also considering NATO's less importance than during cold war, I generally agree with Trump. We should definitely stop expending NATO at first. Then, we need downsizing NATO by kicking out those countries that are not willing to spend their shares. If no European countries are willing to pay their share, we dissolve NATO. It is unlikely though.