Ah that old chestnut. Yes, European NATO countries have long benefited from being backed by US military guarantees. But this was in no way something the US were against. After the cold war, the US were encouraging a move away from national defence and instead towards European NATO members specializing their military for a few specific tasks. This was optimization for supporting the US military in a post-cold war world. The US didn't want a strong Europe, they wanted a Europe dependent on the US:
Now there has been a change, and while it will take years to build up European independent security, the process is ongoing and Trump has ensured it is not going to stop.
We have already started to hear whining from the US about getting exactly what they ordered when European NATO is investing more and more into European-made weapons instead of buying American. Maybe we are not so many years away from export restrictions on some high-tech weapons from the EU to the US, just like the US does not sell it's best weapons to NATO allies.