U.S. airstrikes hit ISIS inside Syria for first time

(CNN) -- U.S. jets began airstrikes in the ISIS stronghold of Raqqa, Syria, early Tuesday, the first strikes against the terror group inside the country since President Barack Obama's announcement this month that he was prepared to expand the American efforts beyond targets in Iraq, a U.S. official told CNN.

The U.S. and "partner nation forces" began striking ISIS targets using fighters, bombers and Tomahawk missiles, Pentagon spokesman Rear Adm. John Kirby said, though he didn't specify a geographic location.

Citing the ongoing operations, Kirby said the Pentagon would not provide additional details immediately.

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<cite class="expCaption">Syrians cross into Turkey to flee ISIS</cite>

All foreign partners participating in the strikes with the U.S. are Arab countries, a senior U.S. military official told CNN. Those nations are Saudi Arabia, the United Arab Emirates and Jordan.

Tomahawk missiles launched from the sea initiated the strike, followed by bombers and fighters, a senior U.S. military official told CNN.

The goal with this first move is to have an initial, definitive blow, the official said, describing the pace of the operation as intense.

Most of the spots hits were hard targets, like buildings, a senior U.S. official told CNN.

With the airstrikes, the United States enters a new level of engagement in the ongoing Syrian civil war. Obama had resisted U.S. military action in Syria, but as the Islamic State in Syria and Iraq made sweeping advances in both Middle Eastern neighbors, calls for such a step grew.

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"I have made it clear that we will hunt down terrorists who threaten our country, wherever they are," Obama said in a September 10 speech. "That means I will not hesitate to take action against ISIL in Syria, as well as Iraq. This is a core principle of my presidency: if you threaten America, you will find no safe haven."

The message of the speech was clear -- it was a matter of when, not if -- the United States would carry out airstrikes inside Syria.

Last week, U.S. officials told CNN that the military had everything in place it needed to strike ISIS inside Syria and was awaiting Obama's go-ahead to do so.

For weeks, intelligence and military targeting specialists have been working around the clock on a list of targets, the officials said. It is unlikely that the President reviewed all the targets individuall, but was presented broad guidance with analysis about the risks of bombing inside Syria, as well as the rewards in terms of attacking ISIS.

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Secretary of Defense Chuck Hagel told the House Armed Services Committee last week that he and Chairman of the Joint Chiefs of Staff Gen. Martin Dempsey signed off on plans to strike ISIS in Syria.

"CENTCOM's plan includes targeted actions against ISIL safe havens in Syria -- including its command and control, logistics capabilities, and infrastructure," Hagel said last week. "Our actions will not be restrained by a border that exists in name only.