IS vows revenge for airstikes that killed at least 70 of its fighters

The United States and its Arab allies struck from the air inside Syria for the first time on Tuesday, killing dozens of Islamic State fighters and members of another group linked to al-Qaida.

"I can confirm that US military and partner nation forces are undertaking military action against ISIL 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, using an alternative acronym for Islamic State.

The US Central Command said that Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates participated in or supported the strikes against targets around the eastern cities of Raqqa, Deir al-Zor, Hasakah and Albu Kamal.

Targets included "fighters, training compounds, headquarters and command and control facilities, storage facilities, a finance center, supply trucks and armed vehicles", the command said.

US President Barack Obama said the participation of five Arab nations in airstrikes against militants in Syria "makes it clear to the world this is not America's fight alone".

Separately, US forces acting alone launched strikes in another area of Syria against a group linked to al-Qaida, the Nusra Front, to "disrupt imminent attack" against US and Western interests by "seasoned al-Qaida veterans", CentCom said.

US-led airstrikes against Islamic State killed at least 70 of its fighters on Tuesday in north and eastern Syria, a group tracking violence in the war said.

Rami Abdulrahman, who runs the Syrian Observatory for Human Rights, said the death toll was likely to be much higher. "The information is the numbers are bigger than that," he told Reuters.

Islamic State vowed revenge for the attacks.

"These attacks will be answered," an IS 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.

US forces have previously hit IS targets in Iraq, where Washington supports the government, but had held back from a military engagement in Syria, where the United States opposes the Syrian government.

Syria informed

The Syrian government said Washington had informed it of coming strikes hours before they were launched. US Secretary of State John Kerry sent a letter to Damascus through his Iraqi counterpart, the Syrians said.

A ministry statement read on state-run television said Syria would continue to attack Islamic State. It was ready to cooperate with any international effort to fight terrorism and was coordinating with the government of Iraq.

Islamic State's Sunni fighters, now equipped with US weapons seized during their advance in Iraq, are among the most powerful opponents of the Syrian government. They are also battling rival Sunni groups in Syria, the Shiite-led government of Iraq and Kurdish forces on both sides of the border.

In recent days, its forces have captured villages from Kurds near Syria's Turkish border, sending nearly 140,000 refugees across the frontier since last week. The United Nations said it was bracing for the flight of up to 400,000 people.

Allies stay out

Some traditional Western allies, including Britain, which went to war alongside the United States in Iraq and Afghanistan, have so far stayed out of the campaign.

NATO ally Turkey, which is alarmed by the rise of IS but also worried about Kurdish fighters and is opposed to any action that might help Assad, has refused to take a military role in the coalition.

France has struck IS in Iraq but not in Syria. A Muslim militant group that kidnapped French national Herve Gourdel in Algeria on Sunday threatened in a video to kill him unless Paris halted its intervention in Iraq.

French Prime Minister Manuel Valls said on Europe 1 radio that French authorities are "doing everything" to try to free the hostage but won't negotiate with his captors.

Russia said any strikes in Syria are illegal without the Syrian government's permission or a UN Security Council resolution. Moscow could exercise its veto in the UN.

Reuters-AFP-AP