When Turkey’s President Recep Tayyip Erdogan visits Washington next week, he and President Donald Trump will no doubt spend considerable time discussing the future of the Syrian-Kurdish People’s Protection Units (YPG), America’s favored contingent in the war against the Islamic State. With U.S. assistance over the past two and a half years, the YPG-dominated anti-ISIS forces have recaptured some 7,400 square kilometers of northeastern Syria from the terrorist group. From Erdogan’s perspective, this strategy, embraced by the Obama administration and now Trump, is helping a Kurdish terrorist group that threatens Turkey’s security and territorial integrity—security and territorial integrity that NATO is supposed to help defend. Erdogan’s likely response: more pressure on America’s Syrian-Kurdish allies, even if that pressure undermines Washington’s goal of reducing the Arab-extremist threat in eastern Syria.

Recent events show how complicated this will be for the Trump administration. After Turkey’s bombing of YPG positions in northern Iraq and Syria on April 25, a U.S. military officer met with a known commander of the Kurdish Workers Party (PKK), an insurgent group that has long been a thorn in Turkey’s side, and has held a spot on the U.S. Foreign Terrorist Organization (FTO) list since 1997. The meeting provoked outrage in Turkey and drew a sharp rebuke from Erdogan. The announcement on Wednesday that the United States would arm the YPG demonstrated that Erdogan has failed to convince the Americans to reverse course with the PYD-YPG, despite intense lobbying.  His visit to Washington promises to be a difficult one for both governments.

As autocratic and intemperate as he is, Erdogan isn’t actually wrong about the commingling of various Kurdish outfits. In a 2013 interview with Osman Ocalan, the brother of imprisoned PKK leader Abdallah Ocalan, Osman claimed that he and other PKK figures founded the Democratic Union Party (PYD), the YPG’s political arm, in 2003 in Iraq’s Qandil Mountains, the headquarters of the PKK. The PYD is also a member of the Kurdish Communities Union, established in 2005 in Qandil by the Kurdish People’s Congress, a PKK organization that the State Department added to the FTO in January 2004. The co-chairperson of the executive council of the Kurdish Communities Union is Cemil Baylik, the acting leader of the PKK. In addition, hardened PKK activists, fighters, and commanders fill the ranks of the PYD and YPG. A YPG fighter told The Wall Street Journal that he had been with the PKK before, and that fighters regularly rotated between PKK armed entities. Iraqi Kurdish Region President Masud Barzani, a close ally of the United States against ISIS, said in March 2016 that the PYD and the PKK are basically the same entity.

Yet, the Trump administration (and Obama’s before him) keep contending, as recently as March 8, that the PYD-YPG and PKK are separate entities. But this has no basis in observable fact. And given the organic links between the YPG and the PKK, the PYD-YPG autonomous zone in northeastern Syria will likely provide strategic depth for the PKK’s ongoing and future fight against Turkey—something Erdogan knows and fears. There are reports out of Turkey already that Kurdish militants aligned with the PKK and PYD organized and trained in YPG-held northeastern Syria for attacks conducted in Istanbul, Ankara, and Bursa, in 2016.

By relying on the YPG in the fight against ISIS, the United States is helping one terror group fight against another. That’s despite its longstanding policy of not working with any organization on the FTO, as it is doing with the YPG, which is effectively synonymous with the PKK. Of course, some argue that the PKK should not be on the U.S. FTO list. An in-depth discussion on the conditions for the PKK’s removal would require months. In the meantime, however, blatantly ignoring the FTO strictures on official U.S. conduct with a listed organization like the PKK and its subsidiaries reflects utter policy incoherence, diminishing America’s credibility on fighting terrorism.

America’s infatuation with the PYD-YPG also allows it to ignore some uncomfortable realities that will haunt it long after ISIS is ousted from Raqqa. While the PYD-YPG organization is secular, it is not democratic. It has repressed political competitors, detained other Kurdish political activists, and detained and harassed independent journalists. What’s more, its emphasis on gender equality, and its insistence on imposing its political agenda, will cause problems for the future governance of Raqqa, the de facto capital of ISIS, and other Arab-majority towns the United States is now helping it seize from a weakened ISIS.

Consider the case of Layla Mohammed, a PYD member and women’s rights activist from the town of Tel Abayad on the Turkey-Syria border. In a conversation, a senior U.S. official spoke with admiration of her dedication and commitment to the cause of women in Syria. Over objections from some Arab community leaders in Raqqa, the PYD- and YPG-dominated Syrian Democratic Forces (an entity that serves, basically, as a fig leaf by Washington to cover the U.S.-backed YPG campaign against ISIS) named Ms. Mohammed co-chair of a new Raqqa administrative council that will rule Raqqa after ISIS is gone.

But Raqqa, more than Damascus, Homs, or Aleppo, is known among Syrians as a conservative Arab city, where many communities retain links to tribal networks extending along the Euphrates and eastwards into the Syrian desert towards Iraq. Traditional norms, including those governing the roles of women, prevail. Many Americans find the constraints placed on Arab women objectionable, and would applaud Ms. Mohammed’s activism. But as the Iraq war should have taught Washington, it cannot impose, either directly or through local proxies, its own social and political norms on conservative Middle Eastern communities without potentially provoking a counter-reaction.

Arab opinions polls from recent years make this tension plain. An unofficial survey of ISIS fighters from 2014 conducted by a Lebanese communications firm showed that defending Sunni communities under attack was the top reason recruits from other Muslim countries joined ISIS. The 2016 ASDA’A Burson-Marsteller Arab Youth Survey highlighted how disputes over how best to interpret Islam and perceptions that western culture is being imposed on Arab societies feeds extremist recruitment. The longstanding Arab-Kurdish ethnic competition and the PYD’s ideological agenda, such as suddenly imposing gender equality, stand to boost extremist recruitment once ISIS shifts to insurgency mode after the fall of Raqqa.

Most worrisome: evidence that Sunni-Arab extremists learn and adapt from their own mistakes. In Idlib province in northwest Syria, al-Qaeda shifted away from the brutal tactics it honed in Iraq from 2004 to 2009. Instead, by transitioning into something of an “al-Qaeda, Version 3.0,” it has reduced violence against local populations, provided infrastructure-service delivery through local administrators, and integrated more with local communities. If the Arab communities of eastern Syria perceive that the PYD-YPG seeks to dominate them,  wiser al-Qaeda and ISIS leaders in Syria may be poised to pick up more recruits and embed in communities, making the coming Arab insurgency harder to contain.

For now, ISIS is still in Raqqa and hasn’t yet shifted into wide-scale insurgency mode. But it won’t be long until Washington will have to decide who will control and govern Raqqa and eastern Syria, and who will pay for it. As Colin Powell told George W. Bush in 2003, if Bush toppled Saddam, America would “own” Iraq and have to take responsibility for it. America may soon have 1,000 more troops on the ground in eastern Syria, and its proxies are seizing new territory from ISIS every week with U.S. support, including a Marine artillery battalion and regular airstrikes. There are even U.S. peacekeepers deployed in Manbij and near Tel Abayad to keep Turkish, Syrian-Arab, and Syrian-Kurdish fighters from shooting at each other. America now effectively owns eastern Syria.

The Obama administration knowingly launched America in this direction, but Trump, who denounced nation-building in his campaign, will pay the larger bills now coming due. America’s difficulties will be even worse if Turkey stokes further anti-PYD-YPG sentiment in this Arab-majority region. Thus, we will need to cut a deal with Erdogan.

The saddest part of all this is that the Syrian Kurds, like so many Middle Easterners before them, think the Americans will protect them from their enemies. They have forgotten the bitter experience of Mustafa Barzani, the Iraqi-Kurdish leader whom the Americans backed in the 1970s against the Iraqi Baathist regime, only to sell them out in 1975 when the U.S.-backed Shah of Iran cut a deal with Baghdad. Henry Kissinger halted the U.S. arms supply to Barzani, and Iraqi forces overran Iraqi Kurdistan. Mustafa Barzani, father of  President Masud Barzani, had to flee and died in exile in the U.S. Especially with presidents like Obama and Trump, the Syrian Kurds of today should expect no better of the Americans.