The table is set for a dramatic head of state visit to Washington this week.

Turkish President Recep Tayyip Erdogan and senior members from the ruling Justice and Development Party (AKP) come to Washington amid considerable tensions in the bilateral relationship. According to sources within Turkey, some Turkish bureaucrats still believe that President Donald Trump can be convinced to change the basic concepts of the U.S. war plan in Syria. The Turkish military — perhaps more well-versed in the specifics of the plan — are skeptical, and are likely preparing options to deal with the threat posed by the Kurdistan Workers’ Party (PKK), a Kurdish insurgent group active in Turkey.

Erdogan is certain to be disappointed. Turkey has no real alternative to the favored U.S. plans to take Raqqa, an important Islamic State stronghold in eastern Syria. Key U.S. decision-makers are aware of Turkey’s concerns and have chosen to pursue a war plan that is anathema to Turkish interests. Erdogan will likely leave Washington with little to show on the Syrian front.

The crux of the disagreement is straightforward: The United States works most closely with the People’s Protection Unit (YPG), the militia for the Kurdish-majority Democratic Union Party (PYD). The PYD, in turn, has administrative links to the PKK, and the core cadre of YPG leaders have spent time with the PKK in the Kandil Mountains in Iraq’s Kurdistan region.

The United States, until last Monday, was providing overt assistance for Arabs grafted on to the YPG’s military structure, collectively dubbed the Syrian Democratic Forces (SDF). The linkage poses obvious problems for Turkey, and political elites across Turkey’s divided political spectrum share little sympathy for the SDF and its military endeavors inside of Syria.

The issue at stake for many Turks is the idea that the the Turkish state could be divided. This sounds absurd to most Americans, but has deep resonance across the political spectrum in Turkey. The legitimization of the PYD in Syria, therefore, is seen as a first step towards international recognition of the PKK, including their demand for autonomy inside of Turkey.

As the battle for Raqqa looms, the United States has pushed ahead with the plan to arm the YPG directly. For an administration accustomed to internal political chaos, the roll out for the announcement has largely proceeded according to a script decided not too long after the election. President Trump pledged to keep elements of his plan to defeat ISIS from leaking. Yet, the broad brush strokes of the battle plan were well known by the time Trump took office: an SDF-led assault, backed by an increased U.S. military footprint in Syria. To breach the city, the SDF would need armored vehicles, anti-tank missiles, engineer support, mine-clearing vehicles, and direct U.S. assistance to help organize logistics and the battle plan.

Pursuant to Section 1209 of the National Defense Authorization Act (FY 2015), Trump was required to notify Congress regarding changes in policy governing the overt training and arming of Vetted Syrian Opposition Groups (VSOs). The YPG, because of its link to the PKK, was barred from receiving overt U.S. assistance from the US military. Trump’s decision to override this ban will soon take effect, clearing the way for more American military support for the SDF.

How We Got Here

Ankara was slow to realize the importance of the YPG — and then the SDF — to U.S. war planners. First in Sinjar in Iraq, and then in Kobane in 2014, YPG cadres were tenacious in their fight against the Islamic State. Assisted by U.S. airstrikes, the YPG refused to give in to the relentless Islamic State onslaught. In Kobane, the YPG eventually turned the tide of the battle.

Importantly, the YPG continued its eastward offensive, taking the important city of Tel Abyad from Islamic State in June 2015. The fall of Tel Abyad was of critical importance for the war against ISIS — the largest number of foreign fighters that travelled to Turkey did so through the Tel Abyad border crossing with Turkey, according to a large cache of Islamic State foreign fighter records documented in depth by the Combating Terrorism Center at West Point. The second most important crossing, near Jarablus, was also a point of concern. The foreign fighter issue was a point of contention between the U.S. and Turkey, with U.S. officials publicly blaming Turkey for being slow to take steps to clamp down on cross-border trade.

Four months later, in October, President Obama authorized the deployment of 50 special operators, and tasked this group with five interlinked objectives. On the Syrian side of the border, the focus was on “enabling new and additional local forces to pressure, take and ultimately hold ISIL’s declared stronghold of Raqqa” and “[s]ecuring the border between Syria and Turkey to reduce the flow of fighters, materiel, and money.” This deployment prompted efforts to build the SDF, along with a parallel effort with Turkey to train and equip groups of Arab and Turkmen fighters to close the “Manbij pocket” — the strip of territory stretching from Azaz to the Euphrates River. Like the concurrent moves with the SDF, these efforts were intended to close the border, and take the fight to the Islamic State.

The train and equip program was troubled from the start. Potential vetted opposition groups and other elements of the Turkish backed opposition were small in number and were required to pledge to fight the Islamic State — and not the Assad regime. The battle-hardened fighters remained with other militia groups and fought alongside two of the more effective militias in the Syrian conflict: the Salafi Ahrar al Sham and the al-Qaeda affiliate then called Jabhat al-Nusra. This further limited the potential pool of recruits, and also branded those that received training from the United States as potential spies or sell-outs for focusing only on ISIL.

The United States also had bureaucratic limitations: To train and equip these groups, the military needed authorities under Title 10 of the U.S. Code, according to an official interviewed about the program. Title 10 governs the role of U.S. military forces and provides the legal justifications for the missions assigned. Title 10 authority, therefore, was needed to give the Department of Defense the legal authority to operate west of the river and to deploy a contingent of Army Special Forces to train fighters in Turkey. This effort differed from a similar effort in Syria, where a different special operations component worked with and through the SDF. The Turkey-based effort, according to two U.S. officials, had an indirect report line, and was therefore susceptible to micro-management from the Obama White House and Central Command (CENTCOM). The SDF-led effort, it seems, had less oversight and therefore had more operational flexibility, suggesting that some elements of this effort were conducted under Title 50 of the U.S. Code, typically associated with covert operations. Thus, one element of U.S. special operations forces had considerably less oversight than the other, most probably owing to the covert nature of elements embedded with the SDF east of the river.

This distinction is important, but may have had only a small impact on the success of the train and equip effort. The broader issue is that these groups lacked a common goal, were poorly motivated to fight in the Manbij Pocket, and had divided command structures. The train and equip groups had also a poor track record against Jabhat al Nusra, clashing with the group on at least two occasions, resulting in the trading of weapons at one point to guarantee safe passage. The YPG, in contrast, has required little American investment, other than the broader effort to graft Arab elements on to the group to create the SDF, according to three different officials interviewed for this piece. The training of Arab elements to graft onto the YPG suffered similar problems, according to a person involved in the program, suggesting that the success of the SDF stems from Kurdish logistics.

The other relevant factor is that Russia intervened directly in the Syrian conflict in late September 2015. Escalating tensions with Moscow two months later, the Turkish military downed a Russian SU-24 bombing the Turkish-backed insurgency on Turkmen mountain. Russia promptly expanded its bombing campaign to include the Marea line, softening up the broader Turkish-backed elements that the American-trained groups had intended to link up with. This sequence of events also prompted Turkey to stop flying missions over Syria — an outcome that has seemingly resulted in Ankara no longer being part of the coalition’s air tasking order (the means used to direct flight operations in multi-country air campaigns).

Despite the challenges, the coalition did try to use elements from the train and equip program to take control of the Manbij Pocket. These efforts failed, setting in motion a sequence of events that have deepened U.S.-Turkish tensions. In late May 2016, the SDF began its push for Manbij, then under the control Islamic State, according to data collected from the Syria Live Map. The offensive went against Turkey’s long-stated redline that it would not tolerate a YPG presence west of the river. In choosing to assault Manbij, the United States was moving forward with its own plan to defeat ISIL, regardless of Turkish concerns. The fall of Manbij prompted Turkey’s cross-border military operation, dubbed Euphrates Shield. This operation was long in the making, and appears linked to Turkey’s decision to mend relations with Moscow, in order to de-conflict military operations in Syria. The United States was apparently the last major power Turkey informed about its invasion of northern Aleppo, reportedly telling U.S. officials some 48 hours before the start of the operation.

Turkey’s military performed poorly in Syria. Its armored units demonstrated poor combined arms tactics. Turkey’s Syrian partners were too few in number to fight along multiples axes. Further, the Islamic State was able to bloody Turkish forces gathered outside of Al Bab. The offensive became bogged down in December 2016, which allowed the Syrian regime to effectively encircle Turkish forces, cutting Ankara from a further push south towards Raqqa. Additionally, in mid-March, Russia brokered an agreement to create a buffer force west of Manbij, ruling out a Turkish expansion of its efforts to take SDF-held Manbij — a goal that Erdogan staked out on multiple occasions.

The Problems with Raqqa: A Predetermined Collision Course

The end of Turkey’s military operation prompted renewed discussions with the United States about a joint operation to take Raqqa, without the SDF. In a series of meetings with Trump officials, Turkey’s Minister of Defense, Fikri Isik, and Chief of the General, Hulusi Akar, proposed a plan that would send somewhere between 3000-5000 Turkish-backed opposition members currently undergoing training in Turkey. This force would join up with a small number of Turkish forces, who would then enter Syria through SDF-held Tel Abyad, push down to Raqqa, and link up with U.S. forces. This plan would that the SDF give a free pass to the Turkish military to travel through a corridor that would also result in Kurdish held territory east of the river being cut in two. This plan was never feasible. The Turkish feeder program has not generated enough forces to take Raqqa, while Ankara’s proposed contribution was viewed with skepticism inside the coalition.

In reality, the Trump administration had the option to siege and take Raqqa with more U.S. conventional forces, or to undertake a much broader effort to train and equip a rival force from Syrian Arabs. Either of these two options could have helped to address Turkish concerns.

However, it would have slowed the campaign against the Islamic State and would have gone against the advice of the commanders on the ground. The slowing of the campaign would also contradict Trump’s own campaign pledge to speed up the war against ISIS. Therefore, the outcome was all but predetermined, with the SDF serving as the only capable ground force currently ready to fight ISIL in an urban environment. All that was needed was to grant the authorities to arm the YPG.

The broader issue is that Turkey — a NATO ally — was unable to convince the broader Washington policy community to disregard the war plan in favor of some sort of compromise. This should serve as a wake up call for officials in Ankara. Erdogan is unlikely to change Trump’s mind. President Trump’s staff are well-versed in this issue and made the decision to push ahead with a plan that most observers knew would upset Ankara. Turkey has few defenders in Washington — a reality that almost always gets lost in the frequent commentary about the image of the United States in Ankara. This matter is not simply about public relations; it is much deeper. Turkey is no longer viewed as a top tier ally by key actors in the U.S. policy debate, and instead is viewed as an irritant who failed to take decisive steps against the Islamic State in the early days of the war.

The meeting with Trump is, in part, meant to reassure Turkey that it remains an important ally. For Turkey, the meeting is a last chance to convince the American president. The reality, however, suggest that the two sides remain vastly at odds over Syria, with little hope for a broader understanding in the near future.

Aaron Stein is a senior fellow at the Atlantic Council’s Rafik Hariri Center for the Middle East.