American airstrikes against up to 20 ISIS targets are under way in Syria, according to Pentagon officials.

"I can confirm that U.S. military and partner nation forces are undertaking military action against ISIL [ISIS] terrorists in Syria using a mix of fighter, bomber and Tomahawk Land Attack Missiles," Pentagon Press Secretary Rear Admiral John Kirby said. "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."

Several Arab nations are involved in the ongoing U.S.-led operation, a defense official said. A diplomatic source identified the nations as Jordan, Saudi Arabia, Bahrain, Qatar and the United Arab Emirates.

Another U.S. official said the Arab nations will be dropping bombs, not just providing support. Up to 20 locations have been targeted in the operation, many of the sites in Raqqa, the official said.

In a national address on Sept. 10, President Obama said the first part of his strategy to counter ISIS was to “conduct a systematic campaign of airstrikes against these terrorists.”

“Moreover, I have made it clear that we will hunt down terrorists who threaten our country, wherever they are. That means I will not hesitate to take action against ISIL [ISIS] in Syria as well as Iraq,” Obama said. “This is a core principle of my presidency: If you threaten America, you will find no safe haven.”