President Obama has hailed the support of Arab nations in air strikes on Islamic State (IS) militants, saying: “This is not America’s fight alone.”
He was speaking hours after the US and five Arab allies launched their first air strikes against IS in Syria.
Activists say at least 70 IS militants and 50 other al-Qaeda-linked fighters were killed in the strikes.
Syrian officials say they were given advance warning of the strikes, but the state department has denied this.
President Obama confirmed Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar took part in the strikes.
He said the US was “proud to stand shoulder to shoulder with these nations”.
IS has seized large areas of Syria and Iraq, and the US has launched nearly 200 air strikes in Iraq since August.
But Monday’s strikes expands the anti-IS campaign across the border into Syria for the first time.
The strikes targeted the group’s main headquarters in its stronghold of Raqqa, north-eastern Syria.
IS training compounds, vehicles and storage sites were also hit in several other areas.
President Obama said al-Qaeda-linked militants, known as the Khorasan Group, were also targeted.
“We will not tolerate safe havens for terrorists who threaten our people,” he said.