Pence says IS has been defeated, only hours after attack kills US forces in Syria

Hours after the Islamic State (IS) group claimed a suicide bombing that ripped through a restaurant in the Syrian town of Manbij, killing dozens of people including a handful of American service members, US Vice President Mike Pence said the militant group had been defeated.

"The caliphate has crumbled and ISIS has been defeated," Pence said in a speech at the US State Department on Wednesday, using a different acronym for IS.

Pence did not directly mention the attack in Syria during his address to nearly 200 chiefs of US diplomatic missions, all of whom gathered in Washington for a speech that sounded more like a campaign rally than the strategic overview of US foreign policy it was billed as.

US Central Command tweeted that two US service members, one Department of Defense civilian and one contractor supporting the DoD were killed and three service members were wounded in the blast, which was claimed by IS through its Amaq propaganda arm.

The Syrian Observatory for Human Rights, a UK-based war monitor, said 19 people died in the attack, while Turkish President Recep Tayyip Erdogan provided a higher death toll, saying 20 people were killed.

The attack comes nearly a month after President Donald Trump's surprise 19 December announcement that he would withdraw about 2,000 US troops from Syria after concluding that IS had been defeated there.

His decision led to the resignation of Defense Secretary James Mattis, who cited policy differences with the president for his leaving.

White House extends 'deepest sympathies'

The plan to pull US troops out of Syria has also led to heightened tensions between Washington and Ankara after critics accused the White House of abandoning Washington's Kurdish allies, who have been credited with leading the fight against IS in the war-torn country.

Almost eight years into Syria's civil war, a Kurdish-led alliance called the Syrian Democratic Forces (SDF) controls a large swathe of territory in the country's northeast, including Manbij.

The unexpected US pullout announcement left Syria's Kurds scrambling to find a new ally in the Damascus government, as they fear losing US support may leave them exposed to a long-threatened Turkish assault.

By mid-afternoon Wednesday, Trump had not spoken out about the deadly attack in Syria hours earlier.

The White House expressed its “deepest sympathies” to those who died, press secretary Sarah Huckabee Sanders said in a statement.

"Our deepest sympathies and love go out to the families of the brave American heroes who were killed today in Syria. We also pray for the soldiers who were wounded in the attack. Our service members and their families have all sacrificed so much for our country," the statement read.

Some US diplomats, speaking on condition of anonymity, told Reuters they were surprised and dismayed at the speech by Pence, who often paused during his remarks as if to invite applause that appeared to grow fainter as he spoke.

"We're not used to being at campaign rallies," said one US official.

Pence said the administration's foreign policy was based on Trump's "America First" agenda.

"No longer will the United States government pursue grandiose, unrealistic notions at the expense of American people," he said.