On paper, the United States and Turkey are on the same side in the fight against the Islamic State jihadists.

But on the battlefield, as a key offensive nears to force ISIS out of its Syrian capital of Raqqa, the two NATO allies could not be further apart in their choice of the means to do the job – an issue that will dominate Secretary of State Rex Tillerson’s meeting with Turkey’s President Recep Tayyip Erdoğan Thursday in Ankara.

Frustration is mounting on both sides, with the US and Turkey backing competing Syrian proxies as the primary attacking force in the Raqqa offensive.

Tensions between the US and Turkey, however, go far deeper than the disagreement over Syria, analysts say, and are fed by diminishing hopes in Ankara that Donald Trump’s succession of Barack Obama would bring a fresh perspective that would lead to a fundamental improvement in bilateral relations.

Mr. Erdoğan and his ruling Justice and Development Party (AKP) expected a more sympathetic hearing from the Trump administration, after years of increasing friction with President Obama over Erdoğan’s authoritarian slide, human rights issues, and the US alliance with Kurdish fighters in Syria.

“The US is pursuing a policy that Turkey hates, no matter who delivers the message,” says Aaron Stein, a senior fellow at the Atlantic Council in Washington. “I don’t really see any overlapping interests. We have drifted very far apart.”

Washington’s choice to lead the Raqqa offensive is the Syrian Democratic Forces (SDF), an umbrella group led by the Kurdish People’s Protection Units (YPG) militia.

But Turkey insists that its own non-Kurdish Syrian proxy force tackle Raqqa, and accuses both the US and Russia of backing a “terrorist” group that is determined to create a Kurdish mini-state, allied with Turkey’s own ethnic Kurdish separatists.

Turkey is demanding the US cut ties with the SDF-YPG and is threatening not to take part in the Raqqa offensive, which is expected to start soon after Turkey votes in an April 16 referendum on the expansion of Erdoğan’s presidential powers.

“It’s going to be Raqqa, Raqqa, and Raqqa,” Dr. Stein, author of "Turkey’s New Foreign Policy," says of Mr. Tillerson’s meeting with Erdoğan. Expectations on the US side are that it will not go well, he says.

“I don’t think there is any real room for maneuver until after Raqqa falls, and the pace of the battle slows down,” says Stein. “Then maybe you can put it back together again, on the broader geo-strategic level and say, ‘OK, the tactical relationship [with Syrian Kurds] is over, let’s work together to combat broader threats.’ ”

Syria may be the biggest bone of contention, but it is only part of a list of Turkish grievances that has caused the escalation of US-Turkey tensions in recent years. They include the arrest Monday at JFK airport of a top executive of one of Turkey’s biggest state-owned banks, accused of facilitating the evasion of US sanctions against Iran.

Turkey is angry, too, that Washington has not deported the Pennsylvania-based cleric Fethullah Gülen, whom Turkey accuses of orchestrating a failed coup attempt last July.

Expectation of common ground

Some in Turkey had speculated that President Trump’s tough and uncompromising talk, his stated commitment to battling ISIS in Syria and Iraq, and his pro-business outlook would prove a close match for Erdoğan that might yield more common ground.

So far, that has not happened. US efforts to improve ties include half a dozen high-level meetings with Turkish officials so far, including visits by CIA director Mike Pompeo and the chairman of the US Joint Chiefs of Staff, Joseph Dunford.

The top American general was quietly taken in mid-February to the base where Turkey is training its own Syrian Arab forces, in a bid by Turkey to convince the US to employ them in the Raqqa battle, instead of the Kurdish fighters, says the Ankara-based analyst Metehan Demir.

“He was to some extent convinced, and he was expected to give an answer to the Turkish side,” says Mr. Demir. “The [US] answer was to help SDF. Therefore there was huge disappointment on the Turkish side.

“One way or another, the US eventually will include Turkey in this game, because without Turkey it’s not that easy to carry out this operation, either with the SDF or any other force,” says Demir. “The problem is … Turkey says it is impossible for its involvement, as long as Kurdish forces will be included.”

Sensitive to Turkey’s domestic politics, the US appears to be holding off starting the Raqqa offensive until after the mid-April referendum. As a sweetener, Tillerson may offer assistance to help rebuild parts of northern Syria occupied by Turkey’s cross-border Operation Euphrates Shield.

A State Department official this week said Washington was “very mindful of Turkey’s concerns,” and that Tillerson would discuss “interim deescalation zones based on cease-fires or other means,” as well as Turkey’s joint peace efforts with Russia and Iran in Astana, Kazakhstan.

Visit is political, not military

Yet there is little sign the Pentagon will turn its back on the Kurdish militia, which has proven the most effective anti-ISIS force fighting in Syria.

On Monday, Erdoğan again scolded the US. “We don’t consider your business with a terrorist organization appropriate taking into account our strategic partnership and alliance in NATO,” he said.

“I think the military front of the Turkish-American relationship is blocked, and does not seem like it will be unblocked,” retired Turkish Brig. Gen. Haldun Solmaztürk told Voice of America Turkish.

Tillerson’s visit “is to keep political relations under control, not to make progress on the military front,” said General Solmaztürk. “It’s obvious that Turkish national interests and American national interests are clashing when it comes to Syria and the Middle East in general.… I am seriously worried about the future of Turkish-American relations.”

Turkey could respond by limiting US or NATO access to its eastern airbase at Incirlik, which has been instrumental in conducting US-led, anti-ISIS air operations.

But analysts say that, even though Turkey has warmed to Russia in recent months – Turkey’s foreign minister is visiting Moscow Wednesday – there is a limit to those ties. Turkey has been surprised to see Russian forces with Kurdish flags in northern Syria, reportedly side-by-side with the Americans in supporting the SDF-YPG. There appears little danger of the US-Turkey feud causing Ankara to turn away from the Western alliance.

In the Raqqa offensive “we see the dark intentions of the militant Kurds” to capture an Arab city and create a “Kurdish federation,” says İlnur Çevik, an aide to Erdoğan writing in the pro-government Daily Sabah newspaper.

“The Americans are thus playing into the hands of the Kurdish militants willingly or unwillingly as they continue to embolden [their] dreams of a mini-state in Syria” that would stretch from Iraq to the Mediterranean, wrote Mr. Çevik.

Did Turkey misread US stance?

The US commander in charge of the anti-ISIS coalition notes that Kurds make up less than 10 percent of the population of northern Syria, and can’t impose their own rule by force.

“I don’t expect any Kurdish units to remain in Raqqa,” said Lt. Gen. Stephen Townsend, in a conference call with reporters from Baghdad Tuesday. The SDF are expanding their Arab elements in preparation for the Raqqa offensive.

“What we have seen as Syrian Democratic Forces have liberated a good 20 percent or more of northern Syria, is they have recruited fighters from the local area. They have led the assault to liberate their own towns and villages,” said Townsend. “Once those have been liberated, they believe the local fighters, Arabs, Kurds, Turkmen alike … they leave them to govern it and they move on.”

Turkey’s leaders “profoundly misread the new [Trump] administration, and the forces they were inheriting, who have a battle plan that’s been on the books for over a year now,” says analyst Stein.

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“The Syria stuff just seems set in stone. The Turks are pushing against forces that are bigger than them within the US government. They must be furious,” he says.

“From the proponents of the YPG strategy, the line is very much, ‘We gave this [Turkey-backed units] a shot many, many times. You didn’t produce forces, and so we just had to keep going.’ The frustration is felt on both sides.”