Mr. Trump ends with a Reagan-like bit of optimism: that the United States can enter a new era of prosperity and power.

That’s an appealing theme at the end of a populist and nationalist speech — but he left questions on the table. Many questions.

Mr., Trump said that the U.S. would do no nation-building but that it would build stability around the world. Hard to know how you do one without the other

He said there were too many weapons in the world, but he talked about developing new nuclear and cyberweapons.

And he talked about rebuilding NATO, and changing its mission, but did not square that with his previous threat to pull out of the organization.

In short, many big, Trump-like themes — but they are in need of fleshing out.