Updated | US did not approve Turkey's Syria offensive, says Mike Pompeo

Updated at 7:39am

The US did not give Turkey a "green light" for its offensive in northern Syria, US Secretary of State Mike Pompeo has said.

Pompeo defended President Donald Trump's decision to withdraw US troops from the border area, which has sparked an outcry at home and abroad.

Turkey has now launched an assault on territory held by Kurdish-led forces.

President Recep Tayyip Erdogan said the aim was to "prevent the creation of a terror corridor" on the border.

Turkish forces plan to make a "safe zone" cleared of Kurdish militias which will also house Syrian refugees.

Kurdish-led forces vowed to resist the offensive and have already clashed with Turkish troops.

The Kurds - who helped defeat the Islamic State group in Syria and were key US allies in that fight, guard thousands of IS fighters and their relatives in prisons and camps in areas under their control. It is unclear whether they will continue to do so if battles break out.

The US military says it has taken custody of two British detainees notorious for their roles in an IS cell that tortured and killed nearly 30 Western hostages.

The two men, El Shafee Elsheikh and Alexanda Kotey, were part of a British cell nicknamed The Beatles.

They have now been removed from a prison run by the Kurdish-led militia in northern Syria.

.@JudyWoodruff: "Does the U.S. take responsibility for whatever the outcome is [in northern Syria], because the U.S. has given Turkey a green light?"

Sec. of State Pompeo: "Yeah, well that's just false. The United States didn't give Turkey a green light." pic.twitter.com/XTFli37OIG

— PBS NewsHour (@NewsHour) October 9, 2019

In an interview with PBS,  Pompeo defended  Trump's surprise decision to pull back US forces, adding that Turkey has a "legitimate security concern" and "a terrorist threat to their south".

He said reports the US had allowed Turkey to launch the offensive were "just false".

"The United States didn't give Turkey a green light," he said.

On Wednesday Turkey officially launched its long-awaited offensive in north-east Syria.

Turkish president Erdogan said on Twitter that "the Turkish Armed Forces, together with the Syrian National Army [rebel groups backed by Turkey], just launched #OperationPeaceSpring" against Kurdish militias and the Islamic State group in northern Syria.

The reports come in the wake of an international outcry that this might pose a threat to US-backed Kurdish forces and to the campaign against Islamic States jihadists.

Erdogan confirmed on Tuesday that the Turkish military "will cross the Turkish-Syrian border shortly," signalling the start of an imminent offensive.

On Twitter, the president's director of communications wrote that US-backed Kurdish militants have two options: "they can defect or we will stop them from disrupting our counter-ISIS efforts."

The Turkish military, together with the Free Syrian Army, will cross the Turkish-Syrian border shortly.

YPG militants have two options: They can defect or we will have stop them from disrupting our counter-ISIS efforts.https://t.co/vQByIUQHQB

— Fahrettin Altun (@fahrettinaltun) October 8, 2019

Turkish foreign minister Mevlut Cavusoglu said that Turkey's sole target was terrorists in the north-east of Syria. "This is our right, stemming from the UN charter, UN Security Council decisions, and international law. Our operation will be carried out in this framework. We will inform the UN and relevant countries, including Syria," he said.

US President Donald Trump announced on Wednesday that US troops in the area will be pulled out and that he was now handing the responsibility for the battle against Sunni jihadists to the Turks.