Instead of looking at the US, let's look at what used to be a relevant ally...
In the eurozone, for example, politicians are hiding the lack of growth behind a growing mountain of public debt and the GDP growth ain't even beating inflation since the 2008 crisis. In 2008 the eurozone represented about 25% of the world's GDP. Now it's not even 15% anymore.
Falling into irrelevancy doesn't begin to describe the state of things for the eurozone: from 25% of the world's GDP to less than 15% in 17 years is more than alarming.
And yet if you look at the eurozone in Euro, it looks like it's been growing since 2008. But it's actually been stuck since nearly two decades now and there aren't signs of anything getting any better in the eurozone. German carmarkers, the number one export of the eurozone, are in huge trouble (with China eating their lunch).
The US and China are, obviously, less fucked than the eurozone but the USA's growth has also been achieved at the cost of a runaway public debt and runaway inflation.
I don't know what protectionism can and cannot do for the US and it's not clear if manufacturing can really come back to the US but one thing is certain: the eurozone is a failure and whatever it is that they did or do should definitely not be copied. Unelected bureaucrats have managed, in 17 years, to drive the eurozone into the ground. It's mostly true for non-eurozone EU countries as well but some, like Poland (which is in the EU but not in the eurozone), are doing fine.
Basically: if you want to slash your part of the world's GDP by 40% in 17 years, do what the eurozone did.
Now we must understand this: the eurozone didn't just slash it's part of the global GDP by 40% in 17 years... They did so while, at the same time, creating a gigantic mountain of public debt and experiencing inflation.
Another 17 years of this, so another 40% loss, and the eurozone would only represent 9% of the world's GDP. And these unelected bureaucrats are so incompetent that I don't discard the possibility that they'll actually be able to crash the eurozone even faster than that. For example at the moment, while german carmarkers are in trouble, EU bureaucrats are hard at work trying to kill them for good.
Anti-americanism and anti-trumpism is a thing on HN but people should really look more closely at what's happening elsewhere.
What about an article from The Economist as to the reasons the eurozone managed to lose 40% of their share of the world's GDP since the 2008 financial crisis?