Trump has a fair point on America's nuclear arsenal. it's in poor shape, and the Pentagon says it'll take some $7.5 billion to fix it. In the last decade, the section of the U.S. Defense Department tasked with maintaining these weapons has seen security violations, personnel issues and, in 2007, even the temporary disappearance of six missiles in North Dakota.
The phrase "America First" was most famously used by Charles Lindbergh's America First committee, the leading voice in opposition to U.S. entry into World War II. In 1940 and 1941, the America First group campaigned around the country for an isolationist policy toward Europe, even as Nazi Germany conquered France. To most Americans, this phrase won't mean much. But for U.S. historians, Trump's foreign policy theme is an odd choice.