The Pentagon decided not to evacuate more than 5,000 people, including U.S. service members and their families, from the naval base at Guantanamo Bay in Cuba as Hurricane Irma closed in Friday.
A special prison at the base also holds 41 detainees captured overseas and held on suspicion of terrorism, including the ringleaders of the Sept. 11, 2001, terrorist attacks.
The base has "initiated its severe weather plans and is preparing to shelter in place," Navy Cmdr. John Robinson, a prison spokesman, said in a statement.
"It has plans and procedures in place to ensure the safety of detainees in its custody during severe tropical weather conditions," he said.
"Due to force protection and operational considerations, we do not discuss details about those plans and procedures."
Irma was on a path to narrowly miss hitting Cuba head-on by moving northward, which factored into the military's decision. The "Gitmo" base is on the Cuba's southeastern shore.
It still is likely to face heavy winds and driving rain.
When the first effects of Irma blew into the base Friday afternoon, personnel were instructed to remain off the roads "unless necessary" and told to secure all outdoor furniture and equipment.
Service members were instructed to watch social media, emails and public radio for further information.
Heather Babb, a Pentagon spokeswoman, said the military would "ensure the safety and security of the detainees" at Guantanamo Bay.
"Tropical weather is an expected part of life in the Caribbean and for our personnel charged with securing the detainee facilities," she said.
"Likewise, they routinely prepare for any contingencies required to safeguard all individuals at the installation in the event that extreme weather impacts the region. There is no intent for the safety of the detainees to come into question during Hurricane Irma."