WASHINGTON — President Trump vowed on Thursday to reinvigorate and reinvent American missile defenses in a speech that recalled Cold War-era visions of nuclear adversaries — though he never once mentioned Russia or China, the two great-power threats to the United States.

While the president infused the new missile efforts with his ambitions for a Space Force, the actual plans released by the Pentagon were far more incremental. As a political matter, Mr. Trump’s speech seemed designed to play well with his base, a tough-sounding call to a new generation of arms that evoked Ronald Reagan’s 1983 “Star Wars” missile defense program.

But the timing was awkward.

The president’s enthusiastic endorsement of new technologies to detect and intercept incoming missiles stands in sharp contrast to his demand, for example, for a decidedly low-tech barrier — a wall — on the southwestern border to stop migrants from illegally entering the United States. And his call for billions of dollars in new spending on missile defenses comes as the government is shut down in a dispute over $5.7 billion for that wall.

“Our goal is simple: to ensure that we can detect and destroy any missile launched against the United States anywhere, any time, any place,” Mr. Trump said.