U.S. Navy fighter jets flying from an aircraft carrier in the eastern Mediterranean Sea bombed 16 new Islamic State group targets in Iraq and Syria on Monday.

Now in their fourth day, the strikes from the Mediterranean have opened a new front in the U.S. air campaign against the militant group.

"We're getting the job done," Rear Adm. Bret Batchelder, commander of the USS Harry S. Truman strike group, told reporters on the ship as the strikes were being conducted.

He said carrier-based F/A-18 fighter jets had released 10 to 20 naval munitions on targets in Iraq and Syria since Friday, when the Truman moved to the Mediterranean from the Persian Gulf to resume bombing militant targets in both countries.

Navy officials gave no details about what targets were hit and destroyed, but said they were largely the same as in previous strikes from the Gulf, with a focus on destroying and eroding the financial base of the Islamic State group, also known as ISIS.

Shifting the Truman to the Mediterranean was intended to demonstrate that the U.S. Navy is ready to respond to threats and hit targets from anywhere in the world, Batchelder said.

If needed, the ship's 72 fighter jets and other aircraft also could be used to hit targets in Libya, where ISIS militants are making big inroads, but that is not why the ship was redeployed to the Mediterranean, Batchelder said.

Batchelder said the fight against ISIS is starting to bear fruit, with estimates showing the U.S. military and coalition partners in 64 countries have retaken about 45 percent of the land formerly controlled by the militant group.

The Islamic State group's oil and gas revenues have fallen to $250 million, he said. In February, State Department spokesman John Kirby used the same estimate to describe the decline in the group's oil income since last summer, before the U.S. began targeting its oilfields and supply routes in Syria.

Batchelder said the Truman also would participate in several military exercises with allies in the Mediterranean before returning to her home port of Norfolk, Virginia, in mid-July. Those exercises would include an air defense exercise with the French military, and a simpler exercise with Morocco.