WASHINGTON -- The United States and five Arab countries began launching airstrikes against Islamic State group targets in Syria for the first time last night, expanding a military campaign against the militants with a mix of fighter jets, bombers and Tomahawk cruise missiles fired from ships in the region.
Residents of the northeastern Syrian city of Raqqa -- the Islamic State's self-declared capital -- took to Twitter to report large explosions and said repeated passes from military aircraft were clearly audible.
U.S. officials said the airstrikes began around 8:30 p.m., and were conducted with Bahrain, Qatar, Saudi Arabia, Jordan and the United Arab Emirates. The first wave of strikes finished about 90 minutes later, but the operation was expected to continue for several more hours, according to one U.S. official, who spoke on condition of anonymity.
Rear Adm. John Kirby, Pentagon spokesman, said late yesterday the decision to strike was made early yesterday by the military, but he added the operations were ongoing and that more details would not be released until after the strikes were finished.
Kirby did not name the partner nations participating in the operation; however U.S. officials have said the United States would not launch this mission alone and some Arab nations had been expected to participate.
It was not clear when President Barack Obama gave Army Gen. Lloyd Austin, commander of the U.S. Central Command, the go-ahead for the strikes or whether the president had approved the individual targets.
The Obama administration has argued that it legally can go after the militants without congressional approval under a 2001-era authorization that was designed for al-Qaida.
Syria's Foreign Ministry said the United States had informed Syria's UN envoy that "strikes will be launched against the Daesh terrorist organization in Raqqa," referring to the Islamic State group by an Arabic name.
The strikes were part of the expanded military campaign that 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 U.S. journalists, and captured a large swath of territory stretching from within Syria to land across northern and western Iraq.
Some of the airstrikes of airstrikes were against Islamic State group targets in Raqqa. Military officials have said the United States would target militants' command and control centers, resupply facilities, training camps and other key sites.
Gen. Martin Dempsey, head of the Joint Chiefs of Staff, told senators last week that two-thirds of Islamic State's personnel -- which the Central Intelligence Agency estimates between 20,000 and 31,500 -- are in Syria.
Defense Secretary Chuck Hagel said he and Dempsey approved the plan.
Activists inside Syria said the targets included not only positions belonging to the Islamic State, but also bases in three provinces of the group's chief jihadi rival, the al-Qaida-affiliated Nusra Front.
Last week at a UN news conference, Hadi Bahra, the head of Syria's main Western-backed opposition group, called for immediate U.S. airstrikes targeting the Islamic State group in Syria, saying urgent action was required "to avert catastrophe."
Meanwhile, Abu Mohammed al-Adnani, an Islamic State spokesman, appeared to issue a rallying cry in a 42-minute audio statement that was released Monday. He called on the group's supporters throughout the world to act on their own initiative to attack Western civilian and military targets in retaliation for the U.S.-led coalition's aerial attacks in Iraq.
Obama is set to preside over an unusual UN Security Council meeting Wednesday aimed at addressing the threat of foreign terrorist fighters. White House aides said they expect the council to adopt a binding resolution that would require UN nations to prevent the recruitment, transportation, financing and equipping of their citizens to help terrorist organizations.
The National Counterterrorism Center has estimated that 15,000 foreign fighters have joined the Islamic State's fight, including 2,000 from Europe and about 100 from the United States.
"In the United States, the FBI has arrested more than half a dozen individuals seeking to travel from the U.S. to Syria to join the fighting there," the center's director Matthew Olsen told senators last week.
Monday, German officials said they arrested a Turkish immigrant who had returned from Syria and charged him with fighting on behalf of the Islamic State. German officials believe as many as 130 German residents have returned after fighting in Syria.