Nationalism is not about blaming others.
In this context it is about having American policy crafted to serve Americans.
Crazy talk to a lefty. Common sense for everyone else.
Well, yes it is.
Hitler was a Nationalist, a Germanic Nationalist. He went around blaming the Jews and blaming the victors in WW1. He was probably right about the latter, but the former... well, that was scapegoating massively.
The Argentinian Junta used the Falkland Islands/Las Malvinas as a way of diverting attention away from their failing economic policies, blaming the UK. This was also done by the previous leader of Argentina, the female Kirchner.
Milosevic in Serbia went all the way back to 1389 to bring up hatred for Kosovo, and decided to decimate Kosovo of Kosovan Albanians, he also went to war with others, turning neighbors against neighbors.
Hutus and Tutsis ended up hating each other in Rwanda.
I could go on and on and on.
I understand that you think Trump's nationalism is about serving American people. However the problem is it won't. The US is strongest when dealing with other countries. It's got rich of doing that. Thinking that turning around and being internal will work is not based on fact at all.
Think of states who are internal. They're not at the top of the GDP pile.
You say "common sense", generally people use "common sense" when they don't have anything to back up their argument.
GDP per country.
List of countries by GDP (nominal) per capita - Wikipedia
According to the IMF
You have Luxembourg in number one. A country which has open borders all around, a country which is very much external. A country with 44.5% foreign population. Then you have Switzerland, while not in the EU, it's in the Schengen Agreement, very much an international country, again, with a high number of foreigners. Then you have Norway, the same as what I said for Switzerland.