() President Trump on Sunday directed federal authorities to expand and reopen Alcatraz, the legendary and long-shuttered U.S. prison in San Francisco Bay, to house today’s “most ruthless and violent” criminals.

In a post on Truth Social, the president said he is tapping the Bureau of Prisons and other federal law enforcement agencies to “reopen a substantially enlarged and rebuilt” version of Alcatraz.

Trump couched his plan it wasn’t immediately known how viable it would be as a way to get tough on crime. He targeted what he called repeat offenders and the “dregs of society.”

“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. That’s the way it’s supposed to be,” Trump wrote.

When did Alcatraz operate?

Alcatraz, also known as “The Rock,” was a federal prison that operated between 1934 and 1963, when it was closed because of high operating costs. The penitentiary was considered especially strict and virtually escape-proof because of the treacherous waters surrounding the island upon which it sits.

Three inmates managed to escape in 1962, but it’s not known if they survived; it became the basis for the 1979 Clint Eastwood film “Escape from Alcatraz.” Another popular feature set at the site was “The Rock,” an adventure starring Sean Connery and Nicolas Cage, from 1996.

Some of Alcatraz’s most notorious inmates included Chicago mobster Al Capone, who served time for tax evasion, and George “Machine Gun” Kelly.

Today, the former prison is a popular tourist and museum destination run by the National Park Service.

A spokesperson for the Bureau of Prisons said in a statement that the agency “will comply with all Presidential Orders.” The spokesperson did not immediately answer questions from The Associated Press regarding the practicality and feasibility of reopening Alcatraz or the agency’s role in the future of the former prison given the National Park Service’s control of the island.

The Associated Press contributed to this report.