The Pentagon is ready to dispatch at least three Navy ships and a detachment of military helicopters to assist Caribbean countries hit by Hurricane Matthew, defense officials said Tuesday.

The powerful storm made landfall Tuesday in Haiti with Category-4 strength, packing winds of up to 145 mph. Pentagon Press Secretary Peter Cook said Tuesday that the aircraft carrier USS George Washington, the hospital ship USS Comfort, and the amphibious ship USS Mesa Verde all may be called in to assist, potentially deploying thousands of U.S. sailors and Marines in the relief effort.

The Pentagon also will move a detachment of nine U.S. military helicopters from Honduras to the Cayman Islands in anticipation of possible hurricane response efforts, Cook said. The move puts them within a few hundred miles of Jamaica, Cuba and Haiti. U.S. Southern Command, with headquarters in Miami, also will establish a joint task force commanded by Rear Adm. Cedric Pringle in anticipation of requests for help.

“This is a serious storm, and while we have not received any specific request for assistance at this point, we do stand ready to provide support in the region as needed,” Cook said.

A Marine Corps spokesman, Maj. Armando Daviu, said the helicopters are a mixture of CH-53E Super Stallions, CH-47 Chinooks and UH-60L Black Hawks. They departed Soto Cano Air Base in Honduras Tuesday carrying members of both a Marine Corps special-purpose task force and a joint task force run by U.S. Southern Command.

Another Marine official, Capt. Jordan Cochran, said that about 300 members of the 24th Marine Expeditionary Unit are traveling from Camp Lejeune, N.C., to Joint Expeditionary Base Little Creek, Va., on Tuesday to deploy aboard the Mesa Verde. The Marine Corps also will make five to seven MV-22 Osprey aircraft available to operate from the George Washington, he said.

The movements were disclosed as the storm roared toward Cuba, east of where the Pentagon maintains a naval station at Guantánamo Bay. About 4,700 service members remained on the base, which also is home to a military prison that holds dozens of terrorism suspects captured in Iraq, Afghanistan and other countries abroad.

Navy Capt. David Culpepper, the commanding officer at Guantánamo, told service members that all preparations for the hurricane had to be completed by 6 p.m. Monday. He said in a phone interview Tuesday that he expected Matthew to arrive with Category 1 strength on the base because it is tracking several dozen miles eastward.

“We’re hunkered down ready for something more than that, but it’s beginning to look less and less likely that it will be significant,” he said.

The military evacuated about 700 military family members and more than 60 pets over the weekend from Guantánamo to Pensacola, Fla., in anticipation of the storm. Some service members were ordered to relocate to safer areas of the base and were preparing to ride out the storm in schools and other larger buildings.

Military officials said that detainees would be kept on the island during the storm. If required, they would be moved to safer structures on Guantánamo Bay.

The storm’s projected path could affect military operations on several bases in coming days. They include Camp Lejeune, N.C., and several installations in and near Norfolk