The Trump budget also proposes putting significant funds into reinvigorating old systems.

For years, strategists have debated whether the United States could abandon its ground-based nuclear missiles, spread out in silos across the West. They are considered highly vulnerable and so old — many of them date to the 1970s — that they are a hazard.

But Mr. Trump has produced a base budget of $1.5 billion in 2021 to prepare for deploying a new generation of missiles in the late 2020s. That is a nearly threefold increase from last year.

In fact, the administration has put so many new projects in front of the Energy Department and the Pentagon that it seems unlikely many of them will get done, at least on the schedule Mr. Trump envisioned in his budget plan. The W93 weapon would not go into production until 2034, or nearly a decade after Mr. Trump would leave office if elected to a second term. Another new nuclear warhead, called the 87-1, a redesign of a 40-year-old thermonuclear weapon made for ground-based missiles, would not begin production until 2030.

“The bottom line is that N.N.S.A. has more work on its plate than it can perform,” Mr. Young said of the National Nuclear Security Administration. “They are attempting to rebuild the entire nuclear stockpile, while building new components. And their history is that they do not perform big projects on time and on budget.”

It is possible that Mr. Trump’s plan could be upended by the next president, or the president after that. But for now, the message being sent abroad is that the United States is back in the nuclear weapons business, either because it wants to bolster its arsenal or because Mr. Trump wants a stronger hand in negotiations.

At the same time, American allies are going in the other direction. France’s president, Emmanuel Macron, said in a speech on Friday that his country’s arsenal had dropped below 300 weapons, and that he would seek other cuts.

“These decisions are in line with our rejecting any type of arms race and our keeping the format for our nuclear deterrent at a level of strict sufficiency,” he said. He also called for “an autonomous and competitive industrial defense base,” so that France is less dependent on American technology.