In 1956, the government created a top-secret document detailing priority targets, identified by latitude and longitude, in the event of a nuclear war between the United States and the Soviet Union. It was a forward-looking document, planning targets for 1959 with a focus on crippling Soviet air power over the short term. It included nearly 200 targets in Moscow alone, including Red Square, as revealed when the document was declassified in 2015.

At the outset of 1956, striking Moscow 200 times would have meant using more than 5 percent of the country’s entire stockpile of warheads. But this was a document looking forward to 1959, by which point the American stockpile had grown from about 3,700 weapons to 12,300. Within another decade, the American stockpile hit its peak, totaling 31,255 weapons in 1967.

Shortly after winning election in 2016, Donald Trump, responding to comments from Russian President Vladimir Putin, pledged to expand the United States’ nuclear arsenal.

We noted at the time that this was a break from the goals of prior administrations, which had focused, successfully, on reducing the number of weapons possessed by the United States and other countries.

As it turns out, the first year of Trump’s presidency continued that pattern. The Federation of American Scientists this week released new figures on the size of the U.S. stockpile. In 2017, the size of the stockpile dropped by 196 and now stands at 3,822 weapons — the lowest since early 1956.

While excoriating the spending bill that he was about to sign into law Friday, Trump championed his administration’s approach to the nuclear capabilities.

“We’re spending a lot of money on nuclear — our nuclear systems, to upgrade, and in some cases brand new, whether it’s submarines — nuclear submarines and others,” he said. “So we’ll have by far the most powerful nuclear force on Earth, and it’ll be absolutely in perfect shape and condition. And hopefully, praise be to God, we don’t ever have to use it. But there will be nobody that’s even close.”

He’s conflating some things in that comment. The delivery mechanisms for nuclear weapons — submarines, aircraft and silos — are one thing. Building a nuclear force that’s the “most powerful … on Earth” is something different. (Trump famously flubbed a question on the nuclear triad during a presidential primary debate.)

Earlier this month, Putin announced new additions to his country’s nuclear systems, including a missile that he claimed could fly for an almost indefinite distance, avoiding American detection systems. Trump made pointed reference to the United States’ capabilities Friday.

“We’re spending a lot of money on missile defense. We have a lot of offense that’s been recently installed. We’re spending tremendous … money on missile defense,” he said. “You understand what that means? Everybody does. With what we have out there, missile defense is very, very important.”

When it comes to stockpile size, though, Russia probably has a slight edge. The FAS estimates that while the United States has more weapons deployed, the Russian stockpile is about 14 percent larger.

While the size of the American stockpile matches that of 1956, its strength doesn’t. “Comparing today’s inventory with that of the 1950s is like comparing apples and oranges,” the FAS writes — “today’s forces are vastly more capable.”

Stockpile size alone, in other words, doesn’t tell us whether ours is the “most powerful nuclear force on Earth.” How Trump measures that isn’t clear, and the government, as a general rule, is loath to provide many details about its nuclear capabilities.

Learning those details can take half a century.