The U.S. military began airstrikes in Syria against the Islamic State in Iraq and Syria (ISIS) on Monday evening, according to the Pentagon.
U.S. Central Command said the strikes were conducted with a mix of fighters, bombers, drones and Tomahawk missiles.
A White House official said Monday night that the president was being updated on the operation.
Bahrain, Jordan, Qatar, the United Arab Emirates and Saudi Arabia joined in or supported the strikes, according to Central Command.
The strikes targeted ISIS training areas, command and control centers, storage facilities, and a finance center, Central Command said.
It also announced that the strikes hit not only ISIS, but a separate terror group, Khorasan.
Central Command said the group is "a network of seasoned al-Qa'ida veterans — sometimes referred to as the Khorasan Group — who have established a safe haven in Syria to develop external attacks, construct and test improvised explosive devices and recruit Westerners to conduct operations.”
"In total, U.S. Central Command conducted eight strikes against Khorasan Group targets west of Aleppo to include training camps, an explosives and munitions production facility, a communication building and command and control facilities," the statement continued.
Pentagon press secretary Rear Adm. John Kirby said that strike, conducted only by U.S. forces, headed off an imminent attack.
"We had information, good information that this group was in the final stages of planning attack, an imminent attack, either against targets in Europe or the U.S. homeland," Kirby said on MSNBC's "Morning Joe" on Tuesday.
“Based on that information and based on the information we had about where they were, and based on information about how they were resourcing themselves in Syria, we took targeted action against them last night," he added.
Kirby said the decision to conduct the strikes was made earlier Monday by U.S. Central Command Commander Army Gen. Lloyd Austin under authority granted to him by President Obama.
The Navy fired 47 Tomahawk missiles from ships offshore, according to Central Command.
The airstrikes are part of the expanded military campaign the president announced nearly two weeks ago, to degrade and destroy ISIS, who have seized swaths of land in northern and western Iraq and Syria, and threatened to advance on Baghdad.
Kirby said, "there was no resistance, no interaction" with Syrian government forces during the operations.
He said the Pentagon has not heard any response from the Syrian government since then.
"The Syrian regime was notified of our intent to conduct operations," Kirby said. "There was no coordination with the Assad regime and certainly no coordination or cooperation military to military."
Obama briefed House Minority Leader Nancy Pelosi (D-Calif.) on the operation, and Vice President Biden briefed Senate Intelligence Committee Chairwoman Diane Feinstein (D-Calif.) earlier in the day.
House Armed Services Committee Chairman Buck McKeon (R-Calif.) was briefed by Defense Secretary Chuck HagelChuck HagelWho will temper Trump after he takes office? Hagel: I’m ‘encouraged’ by Trump’s Russia outreach Want to 'drain the swamp'? Implement regular order MORE on Monday afternoon.
“Our men and women in uniform are once again striking an enemy that threatens our freedom. I pray for their safety and the success of the mission," McKeon said in a statement.
"This is one step in what will be a long fight against ISIL. With strong coalition partners, a capable military, and a clear mission; it is a fight we can win," he said using an alternative acronym for the militant group.
Sen. Saxby ChamblissSaxby ChamblissWyden hammers CIA chief over Senate spying Cruz is a liability Inside Paul Ryan’s brain trust MORE (R-Ga.), the ranking Republican on the Senate Intelligence Committee, was also briefed by Biden, Chambliss said in a statement.
Chambliss, as well as Sen. Marco RubioMarco RubioGOP loses top Senate contenders How does placing sanctions on Russia help America? Republicans play clean up on Trump's foreign policy MORE (R-Fla.), issued statements supporting the strikes.
Rep. Michael McCaul (R-Texas), chairman of the Homeland Security Committee, also issued a statement supporting the president's decision to strike ISIS in Syria.
"To defeat ISIS, we must cut off the head of the snake, which exists in Syria," McCaul said.
— Justin Sink contributed.
— Updated several times, most recently at 8:07 a.m. on Tuesday.