US President Donald Trump said on Wednesday he would devastate Turkey’s economy if Ankara’s operation in northeast Syria wipes out the Kurdish population there.

Asked by a reporter if he was concerned Turkish President Tayyip Erdogan will wipe out the Kurds, Trump replied: “I will wipe out his economy if that happens.”

Earlier on Wednesday, Turkey launched a long-threatened military operation in northeast Syria to remove Kurdish-led forces from the border area and create a “safe zone” to resettle millions of Syrian refugees.

The offensive came after Trump on Sunday ordered US troops to leave the area in an abrupt policy shift that was sharply criticised in Washington, DC.

Responding to the criticism, Trump and the Pentagon made it clear that the US does not support the Turkish operation, but Democrats and many within Trump’s Republican party feared what it would mean for the Syrian Democratic Forces (SDF), who have been the US’s main ally in the battle against the Islamic State of Iraq and the Levant (ISIL or ISIS), in the region.

The SDF is led by the Kurdish People’s Protection Units (YPG), which Turkey considers a “terrorist” group.

Trump said the US does not “endorse” Turkey’s operation, which he described as a “bad idea”.

But he also defended his decision to pull back US troops, saying he was focused on the “big picture” that does not include US involvement in “stupid endless wars” in the Middle East.