It seems to me there is a lot of naivety and misinformation around here.
After the WWII, the democratic, "western" world entered into an agreement, partly written and partly unwritten, with the USA:
- The USA will be a protector of free world and will protect smaller countries against invasions and threats from stronger countries
- The world, namely Europe, will be paying the US for that (financing debt, using $, hosting the US military bases)
Throughout history, Europe has played a pivotal role in stabilizing the U.S. economy, notably during the 2008 financial crisis. European financial institutions acquired risky real estate derivatives from the U.S., and following the market collapse, European governments had to intervene with hundreds of billions of euros to cover the losses.
This is now changing. Trump is publicly declaring that the US army, financed mostly by Europe (and, surprise surprise, by China), no longer serves the world, but only to American national interests. In other words, America is threatening to use the strong military paid for by the world against those nations that finance it.
So, the world, namely Europe, has two options:
a) to continue financing the bully or at best the unreliable and unpredictable ally who will maybe come to help Europe, maybe not and maybe even will attack Europe
b) to get rid off the US bonds (estimated $ 8 trillions just in Europe), to buy real assets instead and create their own force and new alliances
This may be a very quick end of America as we know it. A bankrupt country, long deep depression, no investments from abroad. Other countries will no more buy the US debt nor the US stocks (which are mostly just the IT bubble).
Rather than expressing gratitude to allies for providing the U.S. virtually unrestricted credit for so long, the current administration acts arrogantly and loses credibility on every side.