U.S., backed by Arabs, launches first strikes on fighters in Syria

"I can confirm that U.S. military and partner nation forces are undertaking military action against (Islamic State) terrorists in Syria using a mix of fighter, bomber and Tomahawk Land Attack Missiles," Rear Admiral John Kirby, Pentagon press secretary, said in a statement.

U.S. Central Command said Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates had either participated or supported the strikes against Islamic State targets.

U.S. forces also launched strikes to "disrupt imminent attack" against U.S. and Western interests by "seasoned al Qaeda veterans" who had established a safe haven in Syria, it said, apparently referring to attacks against a separate group.

The Syrian Observatory for Human Rights, which monitors the war in Syria, said at least 20 Islamic State fighters were killed in strikes that hit at least 50 targets in Raqqa and Deir al-Zor provinces in Syria's east.

It said strikes had also targeted the Nusra Front, in the northern provinces of Aleppo and Idlib, killing at least 30 fighters and eight civilians. The Nusra Front is al Qaeda's official Syrian wing and Islamic State's rival.

The air attacks fulfill President Barack Obama's pledge to strike in Syria against Islamic State, a Sunni Muslim group that has seized swathes of Syria and Iraq, imposing a mediaeval interpretation of Islam, slaughtering prisoners and ordering Shi'ites and non-Muslims to convert or die.

Islamic State vowed revenge.

"These attacks will be answered," an Islamic State fighter told Reuters by Skype from Syria, blaming the "sons of Saloul" - a derogatory term for Saudi Arabia's ruling family - for allowing the strikes to take place.

The Sunni fighters, who have proclaimed a caliphate ruling over all Muslims, alarmed the Middle East by sweeping through northern Iraq in June. They shocked the West in recent weeks by beheading two U.S. journalists and a British aid worker, raising fears that they could attack Western countries.

The strikes took place hours before Obama goes to New York for the U.N. General Assembly where he will try to rally more nations behind his drive to aggressively take on Islamic State.

The action pitches Washington for the first time into the three-year-old Syrian civil war, which has killed 200,000 people and displaced millions. U.S. forces have previously hit Islamic State targets in Iraq, where Washington supports the government, but had held back from a military engagement in Syria, where the United States opposes President Bashar al-Assad.

The Syrian government said the United States had informed it hours before the strikes that Islamic State targets would be hit in Raqqa, 400 km (250 miles) northeast of Damascus.

"The foreign minister received a letter from his American counterpart via the Iraqi foreign minister, in which he informed him that the United States and some of its allies would target (Islamic State) in Syria," the Syrian foreign ministry said. "That was hours before the raids started."

A ministry statement read on state television said Syria would continue to attack Islamic State in Raqqa and Deir al-Zor - areas of eastern and northern Syria - and coordination with Iraq was continuing "at the highest level".

The United States has previously stressed it would not coordinate with Assad's government. Obama's position has long been that Assad must leave power, particularly after he was accused of using chemical weapons against his own people last year.

Islamic State's Sunni fighters, now equipped with U.S. weapons seized during their advance in Iraq, are among the most powerful opponents of Assad, a member of a Shi'ite-derived sect. They are also battling against rival Sunni groups in Syria, against the Shi'ite-led government of Iraq and against Kurdish forces on both sides of the border.

Washington is determined to defeat them without helping Assad, a policy that requires deft diplomacy in a war in which nearly all the region's countries have a stake.

The Western-backed Syrian opposition, which is fighting against both Assad and Islamic State, welcomed the air strikes which it said would help defeat Assad.

The targets included Raqqa city, the main headquarters in Syria of Islamic State fighters who have proclaimed a caliphate stretching from Aleppo province in Western Syria through the Tigris and Euphrates river valleys to the outskirts of Baghdad.

Photographs taken in Raqqa showed wreckage of what the Islamic State fighter said was a drone that had been shot down. Pieces of the wreckage, including what appeared to be part of a propellor, were shown loaded into the back of a van.

Jordan, apparently confirming its participation, said its air force had bombed "a number of targets that belong to some terrorist groups that sought to commit terrorist acts inside Jordan," although it did not specify any location.

Israel said it had shot down a Syrian aircraft over air space it controls in the Golan Heights, which Syria confirmed. It was not immediately clear whether the incident was related to the U.S. action.

WEAPONS SUPPLIES, CHECKPOINTS HIT

U.S. officials and the Syrian Observatory said buildings used by the militants, their weapons supplies and checkpoints were targeted in the attacks on Raqqa. Areas along the Iraq-Syria border were also hit.

Residents in Raqqa had said last week that Islamic State was moving underground after Obama signaled on Sept. 11 that air attacks on its forces could be expanded from Iraq to Syria.

The group had evacuated buildings it was using as offices, redeployed its heavy weaponry, and moved fighters' families out of the city, the residents said.

"They are trying to keep on the move," said one Raqqa resident, communicating via the Internet and speaking on condition of anonymity because of safety fears. "They only meet in very limited gatherings."

The addition of Arab allies in the attacks was crucial for the credibility of the American-led campaign. Some U.S. allies in the Middle East are skeptical of how far Washington will commit to a conflict in which nearly every country in the region has a stake, set against the backdrop of Islam's 1,300-year-old rift between Sunnis and Shi'ites.

With the backing of Jordan and the Gulf states, Washington has gained the support of Sunni states that are hostile to Assad. It has not, however, won the support of Assad himself or his main regional ally, Shi'ite Iran.

Traditional Western allies, including Britain which went to war alongside the United States in Iraq and Afghanistan, have so far declined to participate in the campaign. France has struck Islamic State in Iraq but not in Syria.

A Muslim militant group which kidnapped a French national in Algeria on Sunday has threatened in a video to kill him unless Paris halted intervention in Iraq. [ID:nL6N0RN4D1]

NATO ally Turkey, which is alarmed by Islamic State but also worried about Kurdish fighters and about any action that might help Assad, has refused a military role in the coalition.

As part of U.S. coalition-building efforts, Secretary of State John Kerry met Arab and European counterparts in New York ahead of the start of United Nations General Assembly for talks on how to combat Islamic State and how they might participate.

A senior administration official said U.S. plans "to expand our efforts to defeat (Islamic State) were discussed without specifics" during meetings but declined to elaborate.

Several Arab states have powerful air forces, including Saudi Arabia and the United Arab Emirates. Saudi Arabia has also agreed to host U.S. training of moderate Syrian opposition fighters.

Assad's ally Russia, whose ties with Washington are at their lowest since the end of the Cold War, said any strikes in Syria are illegal without Assad's permission or a U.N. Security Council resolution, which Moscow would have the right to veto.

The Kremlin said President Vladimir Putin told U.N. Secretary General Ban Ki-moon on Monday that air strikes on Islamic State bases inside Syria "should not be carried out without the agreement of the government of Syria".

Obama backed away from getting involved in Syria's civil war a year ago after threatening air strikes over the use of chemical weapons. The rise of Islamic State and the beheading of two American journalists prompted him to change course and take action against Assad's most powerful opponents rather than against Assad.

Washington says it hopes to strengthen a moderate Syrian opposition to fill the vacuum so that it can degrade Islamic State without helping Assad. But so far, the opposition groups recognized as legitimate by the United States and its allies have been a comparatively weak force on the battlefield.