And just like that, we have confirmation of the likely source of President Trump's Sunday whim to reopen Alcatraz — which will never happen — and it's the Clint Eastwood classic Escape From Alcatraz from 1979.

The movie was reportedly showing on the local PBS affiliate WLRN in Palm Beach on Sunday morning, about two hours before Trump shot off his Truth Social post from Mar a Lago suggesting that he'll expand and reopen Alcatraz in order to house the country's most hardened criminals. The Hollywood Reporter put this together on Monday, and it's all the more ironic given the Trump administration's vendetta against public television.

"When we were a more serious Nation, in times past, we did not hesitate to lock up the most dangerous criminals, and keep them far away from anyone they could harm," Trump wrote, in part. That's why, he said, he was directing "the Bureau of Prisons, together with the Department of Justice, FBI, and Homeland Security, to reopen a substantially enlarged and rebuilt ALCATRAZ, to house America’s most ruthless and violent Offenders."

Based on a true story of a 1962 escape from the prison, the 1979 film Escape From Alcatraz stars Eastwood as real-life hardened criminal Frank Morris, who orchestrated the escape attempt by four men, three of whom disappeared and were never seen again and one of whom stayed behind. Authorities believed they may have drowned, after trying to use an improvised raft to cross the Bay, but their bodies were never found.

Trump almost acknowledged the Hollywood inspiration for his idea, as the Chronicle notes, when he answered a reporter's question about the asinine tweet on Monday, saying, "Well, I guess I was supposed to be a moviemaker. [Alcatraz] represents something very strong, very powerful in terms of law and order... Alcatraz is, I would say, the ultimate. Sing Sing and Alcatraz, right? The movies."

Trump then incorrectly said that no one had ever escaped the prison. And he made a reference that might have its roots in a shot from the Eastwood film, saying, "One person almost got there, but they — as you know the story — they found his clothing rather badly ripped up. It was a lot of shark bites, a lot of problems."

We don't generally see great white sharks in the Bay, and Trump was clearly just talking out of his ass, per usual. Also, as the Chronicle notes from accounts of his first term, Trump tends to watch four to eight hours of television every day, so of course this is where his mind went while channel surfing.

As we discussed Monday, Trump himself signed a bill into law in 2018 that was meant to shrink the prison population, but Trump knows that his base likes to hear him say things like "throw 'em all in jail" as much as possible, so this was just him riffing on that idea. Historians note that Alcatraz was shut down over 60 years ago because it was too expensive to maintain and was already in a state of decay, and rebuilding the facility would be prohibitively, absurdly expensive.

As a National Park, which it has been since the 1980s, Alcatraz sees around 1.2 million visitors per year, and is one of the most popular tourist attractions in the Bay Area.

Previously: Wiener: Trump's Alcatraz Idea 'Absurd,' Would Be 'Domestic Gulag In the Middle of San Francisco Bay'