This is an adapted excerpt from the Oct. 30 episode of “The Briefing with Jen Psaki.”

Just before his big meeting with Chinese leader Xi Jinping on Thursday, Donald Trump made a surprise announcement, writing on Truth Social: “I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis. That process will begin immediately. Thank you for your attention to this matter!”

Trump’s announcement came out of nowhere. It’s not even clear what kind of nuclear tests he means — or why it’s so urgent to do them now. When reporters tried to get some clarity from the president, he only seemed to make matters more confusing.

“They seem to all be nuclear testing,” Trump said later on Air Force One. “We have more nuclear weapons than anybody. We don’t do testing. We’ve halted it years, many years ago. But with others doing testing, I think it’s appropriate that we do also.”

Again, we don’t know what he’s talking about, because the other nuclear superpowers, Russia and China, have not detonated a live nuclear weapon since the 1990s. America itself has not detonated one since 1992 — 33 years ago. It’s also worth noting that, according to the Congressional Research Service, the U.S. has the capability to resume nuclear testing within 24 to 36 months of an order.

So it’s really unclear what exactly is motivating Trump to do this now. But it is notable — and it might not be a coincidence — that the president’s announcement comes just after the streaming service Netflix released a provocative new movie on this very subject, “House of Dynamite,” which portrays a nightmare scenario in which the U.S. is revealed to be far more vulnerable to a nuclear attack than many would like to believe.

That move is, of course, a work of fiction, and yet the Pentagon was reportedly so anxious over that film, it issued an internal memo arguing all the ways that “the doomsday scenario depicted in the movie is inaccurate.”

So clearly that movie struck a nerve inside the Trump administration. Could it have gotten under Trump’s skin, too? Could it have prompted that surprise announcement about resuming nuclear tests?

We don’t know. But what we do know is that the whole point of having a nuclear arsenal is deterrence. Our nuclear strike capacity is what ensures America’s enemies think twice before taking action against us.

Yet, on Thursday, Vice President JD Vance seemed intent on justifying the need for nuclear tests — so determined to defend his boss’s decision — that he actually suggested that America’s nuclear weapons may not be functioning properly.

“I think the president’s truth speaks for itself,” Vance told reporters outside the White House. “We have a big arsenal. Obviously, the Russians have a large nuclear arsenal. The Chinese have a large nuclear arsenal. Sometimes you’ve got to test it to make sure that it’s functioning and working properly.”

Wait a minute, the vice president isn’t sure our nuclear arsenal is functioning properly? The last thing any member of any administration should do is cast doubt on America’s nuclear capability — but that’s exactly what Vance seemed to do.

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The vice president seemed to realize that in real time — because seconds later, he walked it back, adding: “To be clear, we know that it does work properly, but you’ve got to keep on top of it over time.”

Look, we have no legitimate reason to believe that there are any problems with America’s nuclear capacity. But we have every reason to question how seriously this administration takes its responsibility when it comes to nukes.

We don’t know why Trump decided to announce he was resuming tests of America’s nuclear arsenal. We don’t know what kind of tests he wants to carry out — and frankly, I’m not entirely sure he does either.

Remember, this is the same president who accidentally fired and then had to rehire all the members of the agency that oversees the safety of nuclear warheads in this country, and then furloughed more than 1,000 workers from another nuclear safety agency during the government shutdown.

Let’s not forget, this is also the same guy who said during his first term that he wanted to literally nuke a hurricane. According to Axios, he brought up that idea on multiple occasions.

That doesn’t inspire a whole lot of confidence in his judgment — or his comprehension of one of the most important responsibilities of the presidency.

So, Trump may think he sounds strong and powerful when he talks about testing nuclear weapons. But to everyone else, he sounds not only reckless, but also like he doesn’t really have a clue how any of this works.