Reports: US airstrikes extend to Khorasan Group and Nusra Front

US forces, staging the first strikes against Islamic State militants in Syria, also targeted a separate group plotting an imminent attack against US and Western forces, officials said.

Eight US air strikes were aimed at the hardline Khorasan Group which is made up of former al-Qaeda operatives, the Pentagon confirmed in a statement.

"The United States has also taken action to disrupt the imminent attack plotting against the United States and Western interests conducted by a network of seasoned al-Qaeda 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," the statement said.

In the air strikes against IS militants, the US was aided by Arab allies Bahrain, Jordan, Saudi Arabia, Qatar and the United Arab Emirates.

Unlike, the bombing against Islamic State, however, the attacks on Khorasan were undertaken only by the US, The Independent reported.

The Syrian Observatory for Human Rights, a UK-based watchdog, claimed positions used by the Nusra Front group were also struck in the provinces of Idlib and Aleppo, although these reports have not been confirmed.

The strikes appear to represent an expansion of the U.S. mission beyond the goals outlined by President Barack Obama earlier this month, when he said US military action would be designed to roll back the territorial gains made by Islamic State militants.

The US side of the attack featured a mix of fighter, bomber, remotely piloted aircraft and Tomahawk Land Attack Missiles to conduct 14 strikes against IS, which is also known as ISIL.

"The strikes destroyed or damaged multiple ISIL targets... and included ISIL fighters, training compounds, headquarters and command and control facilities, storage facilities, a finance centre, supply trucks and armed vehicles," the Pentagon statement said. 

A total of 47 Tomahawk missiles were fired by US ships in the Red Sea and the North Arabian Gulf.

Furthermore, the US-led air strikes killed 30 al-Qaeda militants and eight civilians, including children, in northern Syria on Tuesday, the Syrian Observatory for Human Rights said.

Most of the fighters killed in the strikes west of the second city Aleppo were foreigners, and the civilians included three children and one woman, the Britain-based monitoring group said.

The toll came after the Pentagon confirmed eight strikes against "seasoned Al-Qaeda veterans" in Aleppo province in addition to a series of strikes targeting IS in northern and eastern Syria.

The Khorasan Group is believed to refer to an initiative by al-Qaeda's central command in the Afghanistan-Pakistan region to establish a group in Syria of some of its veteran militants to focus on attacks against the West.

Its members cooperate with al-Nusra Front, al-Qaeda's Syria affiliate, using the group's resources and bases, according to experts.

Al-Nusra's focus, however, has so far been on the fight against President Bashar al-Assad's regime and its members are largely Syrian citizens.