The United States military says one of its service members has been killed in northern Syria as Americans are celebrating Thanksgiving Day.

The US military's Central Command (CENTCOM) said the soldier succumbed to his wounds on Thursday after being wounded in an improvised explosive device blast in the town of Ain Issa, 50 km (30 miles) north of Raqqah.

"The entire counter-ISIL Coalition sends our condolences to this hero's family, friends and teammates," said Lieutenant General Stephen Townsend, commander of the US-led coalition, which claims it is fighting against the Daesh (ISIL) terrorist group in Syria and Iraq.

The death came as the people in America were celebrating their national holiday of Thanksgiving.

"On this Thanksgiving, please be thankful that there are service members willing to take up the fight to protect our homeland from ISIL's hateful and brutal ideology," Townsend said.

US Defense Secretary Ash Carter described the death as a "painful reminder of the dangers our men and women in uniform face around the world to keep us safe."

No further details have been provided. US forces are operating in Syria despite Damascus’s objection and without co-ordination with the Syrian government.

Since March 2011, the United States and its regional allies, in particular Saudi Arabia, Qatar and Turkey, have been conducting a proxy war against Syria. US officials often describe the militants fighting against the Syrian government and people as “moderate opposition” forces.

The years-long conflict has left more than 470,000 Syrians dead and half of the country’s population of about 23 million displaced within or beyond the Arab country’s borders.

The United States has deployed hundreds of troops to Syria under the pretext of fighting against terrorism. But, US President Barack Obama on Sunday acknowledged “moderate” militants fighting against the government of Syrian President Bashar al-Assad cannot hold their ground for a long period of time.

He predicted that Syria's second city, Aleppo, was going to soon fall to Syrian forces supported by Damascus’s allies, Russia and Iran.