As Florida prepares for a direct hit from Hurricane Irma, a deadly Category 4 storm with 150 mph sustained winds, the U.S. military has launched an amphibious relief operation into the Caribbean to aid the U.S. Virgin Islands and Puerto Rico.

Irma’s first contact with land occurred earlier this week after approaching perpendicular to the Lesser Antilles before colliding with them, causing widespread damage — and several deaths — on a cluster of the Leeward Islands including Barbuda, Antigua, Anguilla, St. Martin and St. Barthelemy. The death toll is expected to rise. The Dutch, British and French governments have all pledged resources to help with relief efforts, and in recent days, two Dutch ships have arrived at the island of St. Martin, and a British warship is headed toward Anguilla.

The U.S. response has included five warships, helicopters, cargo aircraft, National Guard troops and thousands of pounds of supplies. The U.S. Coast Guard maintains a modest base in Puerto Rico and has auxiliary contingents in St. Thomas and St. Croix. It is unclear how many resources the Coast Guard can commit to the Caribbean as their helicopters and boats will probably be urgently needed in Florida next week.

The amphibious assault ship USS Wasp arrived in the U.S. Virgin Islands on Thursday and had committed its contingent of helicopters to help move patients from St. Thomas to St. Croix and survey damage in the islands, the Pentagon said in a statement Thursday night. A C-17 cargo jet is also evacuating patients from St. Thomas.

The Pentagon also said parts of the 26th Marine Expeditionary Unit, the USS Kearsarge and the USS Oak Hill, were headed to the Virgin Islands and Puerto Rico and would arrive sometime Friday. Both ships were previously helping with Hurricane Harvey relief efforts.  The Marine unit’s landing craft, helicopters and personnel will be primarily dedicated to helping those ashore.

The USS Iwo Jima and USS New York will also be in the area, and the U.S. Army Corps of Engineers is on standby to ensure that shipping lanes running into major ports remain open.

The Pentagon also said that Puerto Rico, the U.S. Virgin Islands and Florida had activated their National Guard detachments to help with search-and-rescue and evacuation operations. There are 5,242 National Guard troops in Puerto Rico, 596 in the U.S. Virgin Islands, and 8,052 in Florida, according to the Pentagon.

To support the recovery efforts, the U.S. Northern Command, the military command responsible for coordinating efforts in North America, has established a constellation of logistics bases in Alabama, New Jersey, Virginia, Georgia and North Carolina. The command has also sent “urban search-and-rescue capabilities” to the Caribbean, the Pentagon said, including food, generators and tens of thousands of gallons of diesel fuel and gasoline that will be staged at Warner Robbins Air Force base in Georgia.