The Pentagon says the United States and partner nations have begun airstrikes in Syria against Islamic State militants, using a mix of fighter jets, bombers and Tomahawk missiles fired from ships in the region.

Pentagon Press Secretary Rear Adm. John Kirby said that because the military operation is ongoing, no details can be provided yet. He says the decision to strike was made early Monday by the military.

The strikes are part of the expanded military campaign that President Barack Obama authorized nearly two weeks ago in order to disrupt and destroy the Islamic State militants, who have slaughtered thousands of people, beheaded Westerners, including two American journalists, and captured a large swath of territory stretching from within Syria to land across northern and western Iraq.

The pentagon plans to strike up to 20 targets including logistics, fuel and weapons depots, training sites, troop encampments, command and control sites, and headquarters for Sunni fighters, NBC News reports.

The U.S. military will deploy manned and unmanned air assets, including F-22s, B-1 bombers, F-16s, F-15s and F/A-18s, NBC News reports. The aircraft carrier USS George H.W. Bush is at the ready in the Persian Gulf, and the USS Arleigh Burke, a guided missile destroyer that fires Tomahawk Land Attack Missiles, is in the Red Sea.

Kirby said in a statement: I can confirm that U.S. military and partner nation forces are undertaking military action against ISIL terrorists in Syria using a mix of fighter, bomber and Tomahawk Land Attack Missiles. Given that these operations are ongoing, we are not in a position to provide additional details at this time. The decision to conduct theses strikes was made earlier today by the U.S. Central Command commander under authorization granted him by the commander in chief. We will provide more details later as operationally appropriate.

(Report compiled with information Associated Press and NBC News)

Click here for the Statement from Pentagon Press Secretary Rear Admiral John Kirby