The new round of U.S. military strikes in Syria announced late Monday by the Pentagon against the Islamic State militant group included many of the same weapons and aircraft the Pentagon has used in recent weeks in Iraq. But it included a new wrinkle, too: the use of Tomahawk cruise missiles launched by the U.S. Navy from the Persian Gulf and the Red Sea.

Navy Rear Adm. John Kirby, the Pentagon press secretary, confirmed the strikes in a statement late Monday. The decision to conduct them was made earlier in the day by Army Gen. Lloyd Austin, the head of U.S. Central Command, Kirby said. The strikes were still ongoing, meaning defense officials were “not in a position to provide additional details at this time,” Kirby said.

U.S. military officials with CENTCOM said early Tuesday that it had launched a combined 47 missiles from two warships, the USS Philippine Sea, a guided missile cruiser, and the USS Arleigh Burke, a destroyer. The first ship was in the Persian Gulf; the second in the Red Sea. The Philippine Sea is part of the USS George H.W. Bush Carrier Strike Group, which includes an aircraft carrier by the same that the U.S. military has been using for weeks to launch airstrikes in Iraq.

The Navy released videos of missiles getting launched from both ships early Tuesday:

The missiles were launched as part of 14 military strikes on Islamic State targets in Syria overnight, defense officials said. They were used as U.S. fighter jets, bombers and drones also dropped ordnance in Syria on militants, their training compounds, headquarters, storage facilities, supply trucks, armed vehicles and a finance center, CENTCOM said.

The U.S. also launched four more airstrikes in Iraq on Monday, bringing the total number since they were authorized there by the White House on Aug. 7 to 194. They’ve been carried out by a mix of fighter jets, bombers and drone aircraft, but the U.S. military had not previously disclosed using Tomahawks against the militants.

The cruise missiles have been used by the U.S. military for decades, most extensively in the 1991 Gulf War against Iraq and around the 2003 U.S. invasion of the same country. But they also have been fired more recently at targets in Libya in 2011, and were put in position in the eastern Mediterranean to launch strikes in Syria in August 2013, as the Obama administration accused Syrian President Bashar al-Assad’s regime of using chemical weapons against its own people.

The Tomahawk strikes in Syria last year were eventually called off, as Obama sought congressional approval. On Sept. 14, 2013, Russia and the United States reached an agreement in which Syria’s declared chemical weapons would instead be destroyed at sea by a U.S. crew on the MV Cape Ray, a cargo ship specifically equipped for the mission.

Two weeks ago, a Navy official said the USS Cole, a Navy destroyer carrying the missiles, was in the eastern Mediterranean, but it does not appear it was used late Monday in the strikes. The missiles also can be launched from U.S. submarines, but defense officials do not commonly disclose where underwater ships in the so-called “Silent Service” are.

The Tomahawk, made by Raytheon, is about 18 feet long and typically carries a 1,000-pound warhead on it. Some versions of it have a range of more than 1,000 miles, Navy officials say. It is typically considered ill-suited to hit moving targets, but can hit stationary targets with precision.

UPDATE, Sept. 23, 7:25 a.m.: This post was updated with new information provided by the U.S. military.