Although it is not clear exactly what the cease-fire agreement stipulates and who will be supervising it, the regime of Syrian President Bashar al-Assad has agreed to abide by it and will be participating in the proposed talks in Astana, Kazakhstan. These are clear signs of Assad’s acquiescence to the Russia-Turkey initiative.

Russian-Turkish cooperation, which was evident on the ground in Syria with the evacuation of opposition groups from Aleppo, has sidelined the United States and Europe. Following that move, Moscow and Ankara guaranteed a Syria-wide cease-fire starting Dec. 30.

After hearing the same views from several sources in Ankara, it is clear that the rift between Ankara and Washington over the Syrian crisis is becoming a crisis in itself, one that could have serious ramifications on the ground and in the diplomatic arena.

When asked about the state of relations between the United States and Turkey, a veteran Turkish diplomat who did not want to be identified told Al-Monitor, “Relations on the ground are not warm. Diplomatic developments occur nonstop. Unpredictability, ambiguity and a serious crisis of confidence dominate. It is certainly the worst crisis between the United States and Turkey since 2003 .”

Cooperation between Ankara and Moscow is also indicated by the Turkish military command's statement that the Russian air force bombed Islamic State (IS) targets south of al-Bab, Syria, on Dec. 28-29, in support of Turkey’s Operation Euphrates Shield.

This was the first time Russia had provided air support for Euphrates Shield, which has been going on for some 130 days, claiming the lives of 40 Turkish soldiers.

Ankara, assisted by the Free Syrian Army (FSA), has been trying to expel IS from al-Bab for 40 days and is now at a critical threshold. The operation that was launched Aug. 24 with 600 soldiers (two reinforced mechanized battalions and 10-12 special forces teams) today has reached a strength of 4,000 Turkish soldiers. With its current order of battle around al-Bab, the Turkish army has exceeded the strength of the FSA, which was supposed to be primary ground force. That is critically important, because some FSA elements have withdrawn from combat and because of their lack of discipline in the field, Turkish commandos are now engaged in front-line fighting against IS.

Turkish troops are trying to enter al-Bab from six points in the town’s north and west. The siege is not air-tight, as al-Bab’s east and southeast are still wide open. If IS wants, it can easily withdraw from al-Bab but — as it is doing at Mosul — it seems determined to stay and fight. IS has evacuated its dependents from al-Bab while moving in reinforcements from Raqqa — a sure sign that it will be digging its heels in al-Bab. In addition, the Syrian national army, which recently took over control of Aleppo, is close to al-Bab. Both Turkish and Syrian forces are avoiding contacts so as not to trigger a new clash. But that risk is still there.

The siege of al-Bab makes the Turkish army the world's third conventional force engaged in actual warfare against IS. Adverse weather conditions at al-Bab have been allowing only occasional air support. Moreover, there are reports the Turkish army is having logistical, supply and evacuation problems. Nevertheless, Ankara is determined to capture al-Bab. It appears Moscow has been persuaded, as seen from its recent air support. The coalition purportedly set up to fight IS is not contributing anything to Turkey’s al-Bab operations, which have inflicted the heaviest casualties on IS and broken its back.

As the siege of al-Bab is prolonged, the crisis between Ankara and Washington amplifies. On Dec. 27, President Recep Tayyip Erdogan stressed Turkey has not been getting adequate support from the US-led coalition forces. He accused coalition forces of supporting IS, the Kurdish People's Protection Units (YPG) and the Kurdish nationalist Democratic Union Party (PYD) and so, "We will cut our own umbilical cord” and sever ties with the coalition, he said.

The US reaction came Dec. 28 in an unusually strong statement from the US Embassy in Ankara that said the US government is not supporting IS and has not supplied weapons and explosives to YPG or the Kurdistan Workers Party (PKK).

This was the first statement of its nature from the embassy that triggered an equally stern reaction from Erdogan. On Dec. 29, he said, “In our al- Bab operation, we do not get the slightest support from NATO, from so-called allied countries that have forces in the region.”

With widely divergent goals on the ground and the growing crisis of confidence between them, it is not possible for Turkey and the United States to coordinate an operation in Raqqa. That is why the Kurdish-led Syrian Democratic Forces (SDF) have suspended their attacks against Raqqa. It now appears that the outcome west of the Euphrates River and the future of al-Bab will also decide the future of Raqqa.

Moreover, the "Moscow Declaration" signed Dec. 20 by Iran, Russia and Turkey recognizes the territorial integrity of Syria and does not allow for the PYD's demand for autonomy in northern Syria. But by that same declaration, Ankara appears to recognize the sovereignty of Damascus, including in the north of the country. In other words, even if Turkey captures al-Bab from IS, it may have to hand it over to the Syrian government. Next is likely to be an imminent crisis over Manbij, which is still controlled by the US-supported Kurdish YPG, despite Turkey’s persistent demands for the Kurds to leave.

Why is Ankara so tough on Washington?

There are four reasons. First is President Barack Obama's consideration of the PKK-linked YPG force as a local ally in the fight against IS. In Ankara that is perceived as "Obama prefers the PKK to us."

The second reason is domestic politics. Despite all these foreign policy issues and Syrian affairs, Ankara’s main political agenda in the first months of 2017 will be the highly contentious matter of Erdogan's leadership transition to the executive presidency. Any success or failure in foreign policy issues will be used for domestic consumption — Erdogan will now have two ideal scapegoats in case things do not go well at al-Bab: the United States and NATO. Erdogan will easily market a narrative of, "The United States has spoiled our goals at al-Bab," in case of a failure. That will allow him a gracious escape from domestic pressures.

The third reason is Ankara’s wish to pressure the incoming Trump administration regarding PYD and PKK matters before Jan. 20. The goal is to force Trump's people to choose between supporting Turkey or the PYD and thus compel Washington to end its support of the PYD.

The final reason is Russia. With this harsh rhetoric toward the Obama administration, Ankara seeks to institutionalize its "pop-up alliance" with Russia. Ankara is likely to suggest that Russia has taken great initiative during this transition period while the United States waits in the wings for Jan. 20. Moscow needs Turkey to get the European Union and NATO into a crisis marked by an uncertain outcome. Here, as a regional actor in the West's camp for both the economy and security, if Turkey changes its geopolitical (NATO) and geo-economic (EU) orientation, it will further accelerate the tectonic changes proposed by Russia in the region. Simply put, Russia is delighted that its honeymoon with Turkey has created trouble in the West’s security system.

It is therefore not surprising that the eyes of Moscow, Washington, Tehran, Damascus and definitely Ankara are trained on al-Bab. How will the Turkish army perform there? How will Turkish diplomacy handle military success or failure there? We will learn soon enough.

Editor's note: This article has been updated since its initial publication.