'Not America's fight alone'

Obama made a brief statement in front of reporters before heading to New York to attend the UN's General Assembly, where he will be trying to drum up more support for US military action against territory held by the self-proclaimed "Islamic State" (IS) in Iraq and Syria.

Obama said that "over 40 nations have offered to help" and that the US was "proud to stand shoulder to shoulder with its allies," which include Saudi Arabia, Qatar, Bahrain, Jordan and the United Arab Emirates (UAE).

He said the strength of the coalition showed that "the fight against Islamic State was not America's alone."

He also said that fight would "take time" and that there were "challenges ahead." Obama added that he would "continue building support for the coalition."

Earlier on Tuesday, the USlaunched its first airstrikes on IS targets in Syria, less than two weeks after Obama announced he had approved an expansion of the campaign against the IS group to include action in Syria in addition to the US airstrikes in Iraq.

'Imminent attacks'

Separate airstrikes were also launched on targets associated with another hardline, Islamist group, an al Qaeda offshoot often called Khorasan. The US Pentagon said it had "taken action to disrupt the imminent attacks plotting against the US and Western interests" by what it called "seasoned al Qaeda veterans."

So far, neither NATO nor any Western allies have joined the US military campaign in Syria, although there are reports that the UK is considering the option. UK Prime Minister David Cameron is expected to speak at the United Nations on Wednesday.

The IS jihadists have lost at least 70 fighters in the Syrian strikes, a group monitoring the conflict in Syria said on Tuesday.

"The US planes carried out at least 20 strikes targeting headquarters, checkpoints and bases for the Islamic State group in the city of Raqqa as well as on its eastern and western outskirts," the Britain-based Syrian Observatory for Human Rights said, adding that an additional 50 al Qaeda terrorists were also killed in the strikes.

Strikes were also carried out on the towns of Tabqa, Ein Issa and Tel Abayad on the Turkish border, Observatory head Rami Abdurrahman said.

Eight civilians, including three children, were also among the dead, he said.

IS has already warned the strikes would meet with a harsh response. On Monday, an IS-linked Algerian group on Monday threatened to kill a French hostage unless Paris stopped its involvement in airstrikes in neighboring Iraq.

The Syrian government said it had been informed of the impending airstrikes. The US government said it only provided notification via the United Nations: "We did not request the regime's permission. We did not coordinate our actions with the Syrian government," State Department spokeswoman Jen Psaki said.

The US has ruled out working with Syria's Bashar al-Assad to fight IS, whose fighters are among several armed groups fighting in Syria's civil war.

ng/msh (Reuters, AFP, AP)