ISTANBUL — The U.S. acknowledged on Wednesday that it has been supporting Kurdish forces in Syria with American aircraft deployed in Turkey, adding another tangle to its strategy to defeat the Islamic State group that hints at the precariousness of the entire campaign.

Col. Steve Warren, a spokesman for the U.S. campaign against the extremists in Iraq and Syria, detailed that decision in a press briefing on Wednesday. The U.S. announced on Oct. 30 that it had based A-10 fixed-wing aircraft at Turkey’s Incirlik air base in the country’s southeast, Warren said. Those aircraft have since provided air support for Syrian fighters in a Kurd-Arab coalition in battles against Islamic State positions in northeast Syria’s Al-Hawl region.

Though the U.S. has launched airstrikes to help Kurdish fighters in Syria fight the Islamic State since last fall, Warren’s comments appear to be the most public admission that it is doing so from a base in Turkey — a NATO ally that is skeptical of the Syrian Kurds and only granted the U.S. full flight capabilities at its Incirlik base this past July. Col. Christopher Garver, a public affairs officer for the anti-ISIS campaign, told HuffPost in a Friday email that U.S. flights out of Incirlik have previously aided Kurdish fighters as well.

Warren was careful to note that the ground forces the U.S. was supporting were under the umbrella of the Syrian Democratic Forces, a recently formed alliance of Kurds, Arabs, Turks and Syrian Christians announced just last month. The Arab component of those forces was involved in the anti-IS offensive, which “is important because Al-Hawl is predominantly an Arab area,” Warren specified.

But that Kurd-dominated coalition is widely seen as a politically convenient invention, cobbled together so the U.S. can funnel significant support to effective Kurdish fighters and their allies — as it did with an Oct. 12 airdrop — while saying it is engaging Sunni Arabs, the majority community in Syria.

Talk of the new force gave Washington cover to send arms that could be used against IS without angering Turkey, a State Department official told The WorldPost soon after the airdrop. One administration official called the approach a “ploy” in a conversation with Bloomberg View. And a New York Times reporter who visited the northern Syrian regions home to the new alliance published a damning report on Nov. 2 that said the loosely aligned Syrian Democratic Forces exist “in name only.”

While Turkey and the Syrian Kurds share the goal of undermining the Islamic State, the two U.S. partners deeply mistrust each other. Turkey accuses the dominant political group among Syria’s Kurds, the PYD, of being a branch of a Kurdish militant organization called the Kurdistan Workers’ Party, or PKK. The PKK has waged war on Ankara for three decades in the name of Kurdish rights.

Many Kurds, meanwhile, believe Turkey has aided the rise of extremists during the Syrian civil war and note that Kurdish forces have done more to damage IS on the ground than any Turkish action has. Though these tensions have mostly been expressed verbally, Turkey shelled Syrian Kurdish positions on Oct. 27

Analysts worry Washington’s new maneuver could lose either the support of the Kurds — who are reportedly attempting to strengthen ties with Russia, now a key player in the Syrian war — or the Turks, whose military and geographic position make them key to any effort to change the situation in Syria.

Washington’s balancing act between Turkey and the Kurds has worked thus far. But its willingness to now publicly acknowledge support for the PYD from Incirlik could force it to choose between reducing support to the Kurds, the strongest anti-IS force, or placing more pressure on the Turks, who have great influence over the situation in Syria.

“We’re not trying to cover anything up,” Warren said during his briefing when asked by a reporter to respond to the New York Times report. “We’re providing weapons, or in this case, ammunition, to the Syrian Arab coalition. That’s what we said we’re doing, that’s actually what we’re doing.”

A Turkish official made clear to The WorldPost that his government remains worried about the Kurds in Syria.

“We are deeply concerned about the PYD’s links to the PKK,” the official said. Turkey ended a ceasefire with the PKK in July and has been striking the group in Turkey’s Kurdish-majority southeast and in Iraq ever since. The Kurdish militants have claimed responsibility for frequent attacks on police forces and soldiers. Today, the PKK formally ended a one-month ceasefire, citing the state’s “war policy.”

Ankara shows no evidence of letting up after Sunday’s election, in which President Recep Tayyip Erdogan’s Justice and Development Party won back majority rule after painting the campaign as a choice between chaos and stability. Erdogan has vowed to “liquidate” every PKK fighter.

Turkey’s government was not yet prepared to comment on the U.S. strikes launched from Incirlik, however, the official added.

“Another concern is that divisions among opposition forces will ultimately serve the regime’s interest,” the official added, vocalizing a commonly reiterated state allegation that the Kurds care more about their own interests than the broader future of Syria.

Turkey is a staunch opponent of Syrian dictator President Bashar Assad, and it supports a range of Syrian Arab groups that are trying to bring down his regime. Ankara and many members of those Syrian opposition groups are wary of the Kurds because they have allowed some regime forces to remain in the Kurdish city of Hasakah, and because they believe the Kurds want a de facto break-up of Syria.

Arabs in areas captured by the Kurds with U.S. support have also reported abuse at the hands of Kurdish forces, in interviews with outlets including The WorldPost and advocacy organizations like Amnesty International. Those allegations suggest that the Turks may have a point: If Washington does empower the Kurds without real engagement with Sunni Arabs, it could push many Arabs into the embrace of the Islamic State or other extremist, anti-Western groups in Syria.

The U.S. appears to be managing Turkey’s concerns by tacitly agreeing that Syrian Kurdish forces will not be allowed to pass into areas west of the Euphrates river, according to Aaron Stein, a Turkey expert at the Atlantic Council.

Turkey is nervous that the success of the Syrian Kurds will inspire Kurds in Turkey to try and carve out their own statelets, and it pointed to the Euphrates as a red line when announcing its  recent attacks on the Syrian Kurds. Ankara fears Syrian Kurdish forces will connect the areas they control in northeast Syria to their third region, or canton, in the northwest, thereby creating a powerful Kurdish corridor along the Turkey-Syria border.

The focus on vanquishing the Islamic State, which U.S. officials say will only happen with help from the Syrian Kurds, puts Turkish policymakers in a difficult position.

“In any case, Turkey is certainly indirectly aiding the YPG’s advance east of the Euphrates,” Stein told The WorldPost, using the acronym for the Syrian Kurds’ fighting force. “American drones provide intelligence, surveillance and reconnaissance for these missions, and tankers based at Incirlik most certainly refuel U.S. bombers flying from Qatar.”

Max Hoffman, a policy analyst at the Center for American Progress, told The WorldPost that the U.S. seems largely willing to pursue its goal of bringing down IS regardless of Turkish sensitivities.

“It seems unlikely to me that coalition air controllers would ignore a credible ISIS target relayed by YPG on the ground, or divert coalition aircraft from further away, just because the closest coalition airplane was launched from Incirlik,” Hoffman wrote in a Wednesday email. “But I have no way of confirming that, and it’s certainly in the U.S. interest to allow Turkey to preserve that useful political fiction [that the Kurds are not supported from Incirlik] (if it is, in fact, a fiction).”

The U.S has struggled to find reliable partners against the Islamic State on the ground other than the Kurds and an array of Arab-dominated groups the CIA has armed to fight Assad. In early October, the Obama administration announced that a $500 million Pentagon program to train anti-IS Syrian rebels had largely failed and was being restructured.

The White House’s approach now seems to be to support the Kurds and nationalist Arabs in the north as intensely as possible. It announced on Oct. 30 that President Barack Obama would deploy dozens of American special operations forces to northern Syria to coordinate airstrikes and arms supply.

The war in Syria has claimed at least 250,000 Syrian lives. With no end in sight to the conflict, IS remains in control of large tracts of land and the Assad regime continues to kill civilians daily, prolonging a conflict that has forced millions to seek refuge in neighboring countries and fueled the largest mass migration of people since World War II.

International players involved in the conflict — either supporting Assad or the opposition to him — are holding negotiations to work out whether the dictator can be removed so that a more stable Syria can be established, but those talks have yet to bear fruit.

The latest round, involving the U.S., Turkey, and states like Russia and Iran that are helping Assad, concluded without significant progress last week.

This story has been updated to include Garver’s comments about ealrier U.S. aid to Kurdish fighters. 

Sophia Jones reported from Istanbul and Akbar Shahid Ahmed reported from Washington.