Ankara: Turkey is seeking US support to lead a ground offensive against Daesh’s main stronghold in Syria, a Turkish official said, a move that could give President Recep Tayyip Erdogan more influence in the conflict and undermine Kurdish groups linked to separatists he’s fighting at home.

Troops and Syrian rebels loyal to Ankara would advance on Raqqa through areas controlled by Kurdish fighters whom Turkey classifies as terrorists, the official said on condition of anonymity to discuss the confidential talks. The attack could start within a month but hinges on US support, which would include airstrikes and intelligence sharing, the official said.

A go-ahead by the Trump administration would bring an immediate gain for Erdogan by signaling that the US no longer sees Kurds as an essential element in the fight against Daesh, a view that has infuriated its North Atlantic Treaty Organisation (Nato) ally. Turkey, embroiled in a three-decade conflict with Kurdish separatists, regards Kurdish attempts to establish autonomy in northern Syria as a direct national security threat.

The proposal, however, may face opposition from people who still consider Kurdish fighters the most effective force against Daesh in Syria, said Ozgur Unluhisarcikli, who runs the Ankara office of the German Marshall Fund, a think tank.

“There are some people in Washington who think that PYD is more reliable compared to what Turkey is proposing on the ground,” Unluhisarcikli said by phone from Istanbul on Tuesday, using the acronym of the main Kurdish militant group in Syria.

After a flurry of terrorist attacks blamed on Daesh, Turkey deepened its involvement in the Syrian war in August, sending troops across the border to create a so-called safe zone of 5,000 square kilometers. More than 70 Turkish soldiers have been killed in the operation.

Erdogan said on Tuesday in Istanbul that troops are on the verge of capturing the town of Al Bab, a Daesh stronghold. He’s also asked the US to persuade Kurdish groups to withdraw from the border town of Manbij.

“Manbij belongs to Arabs,” he said.

Turkey is proposing that its soldiers and allied fighters from the rebel Free Syrian Army attack Raqqa using a route that passes through the border town of Tal Abyad, currently under PYD control. The city is the capital of Daesh’s self-declared caliphate and lies about 100 kilometres south of the Turkish border.

“Turkey has two objectives here, one of them is to prevent Kurdish autonomy in northern Syria, the second one is to gain leverage in Syria so that Turkey can play a bigger role in the future of this country,” Unluhisarcikli said.

Defence Department spokesman Eric Pahon called Turkey “a trusted ally”, saying the US is regularly in contact with the Turkish government and military. But he said he had no information about Turkey’s proposal and couldn’t confirm if Turkey had asked the US about it.

Pahon said the Syrian Democratic Forces, an umbrella group that includes Kurdish fighters, and the Syrian Arab coalition are the partners on the ground that the US considers most useful in taking Raqqa. But “if Turkey wants to throw their hat in that ring, that’s a discussion we need to have with the government. The contents of those discussions we wouldn’t really talk about” publicly, he said in an interview on Tuesday.

Air Force Col. John Dorrian, a spokesman for the US-led coalition against the Daesh group, added in an email that “coalition military leadership maintains frequent communication with Turkey and those discussions also occur at diplomatic levels, but we have no new information to release about the way ahead for Raqqa at this time.”

Three years after a lightning rise that helped reshape the course of conflicts in Syria, Iraq and Libya, Daesh is on the retreat, ceding territories in the three countries. After months of planning, Iraqi forces, backed by a US-led coalition and pro-Iranian militias, have started an offensive to retake Mosul, the radical group’s stronghold in Organisation of the Petroleum Exporting Countries’ second-biggest oil producer.

Turkish Prime Minister Binali Yildirim on Tuesday reiterated his government’s opposition to any Kurdish participation in an attack on Raqqa.

“Turkey can’t be side by side with terrorist organisations,” he told ruling AKP party lawmakers in parliament.