The December 19, 2018, announcement of the US withdrawal from northeastern Syria was heralded as Washington’s concession to Turkey’s President Recep Tayyip ErdoGan, giving him a green light to eradicate the PKK-affiliated Kurdish forces of the People’s Protection Units (YPG). However, Turkey’s planned intervention to create a “safe zone” in Syria east of the Euphrates River has been complicated by the recent reconciliation of key Arab nations, with the regime of Bashar Assad, bolstering Moscow’s opposition to Turkey’s ambitions. This alignment weakened Erdogan’s bargaining position in his January 23 Moscow meeting with Russian President Vladimir Putin, and may force Turkey to accept alternative arrangements based on the 1998 Adana Protocol between Ankara and Damascus. Using 2,200 Special Forces and air power, the US created a 19,700 sq.m. (51,000 sq.km.) zone of deterrence, protecting the Syrian Democratic Forces (SDF) spearheaded by YPG fighters. When US troops depart, Ankara plans to establish a Turkish-controlled safe zone into northeastern Syria extending 20 miles (32 km.) deep and 285 miles (460 km.) wide. Turkey claims that Washington acceded to its plans, however, official statements from the Trump administration dispute this.Moscow looks askance at Turkey’s plan, as the Kremlin’s end-game is for Bashar Assad’s regime to regain all of Syria’s territory. The city of Manbij has become a focal point of the Turkey-Russia jockeying, and is to be evacuated by both the US and YPG under the Turkey-US Manbij “road map agreement.” Turkish troops and their Syrian allies now face Russian troops backing the Syrian government in a race to claim the city.While the trilateral Astana dialogue between Ankara, Moscow and Tehran has thus far accommodated Turkey’s ambitions, the disappearance of opposition to the US presence as a unifying factor in the Syria equation has brought the divergence of interests between Turkey and the other two Astana guarantors to the fore.On January 16, Russian Foreign Minister Sergei Lavrov foreshadowed Moscow’s opposition to the plan. “We are convinced that the best and only solution is the transfer of these territories under the control of the Syrian government,” he stated. Obliquely referring to Turkey’s planned intervention, Lavrov added, “We welcome and support contacts that have now begun between Kurdish representatives and Syrian authorities so they can return to their lives under a single government without outside interference.”Turkey’s position vis-à-vis Russia is further weakened by Turkey’s failure to eliminate from Idlib Province the Hayat Tahrir al-Shams (HTS) militant coalition led by Syria’s former al-Qaeda affiliate Jabhat al-Nusra. In accordance with their September 2018 Sochi agreement, Turkey and Russia established a jointly-monitored demilitarized zone in Idlib, preventing Syrian and Russian Air Force attacks on Turkish troops and the forces of the Turkish-backed National Liberation Front coalition, on condition that the NLF under Turkey’s supervision would dislodge HTS from the buffer zone.After a 10-day HTS offensive, the defeated NLF ceded control of all its positions to HTS on January 10, 2018, allowing Jabhat al-Nusra to secure its hold on northern Idlib, as NLF fighters apparently had shifted their focus to preparing for the upcoming battle of Manbij.On January 18, Lavrov expressed the Kremlin’s consternation, “It also worries us that in Idlib, contrary to the agreements on creating the demilitarized zone there, Jabhat al-Nusra dominates and violates the demilitarized zone. About 70% of this territory is already occupied by terrorists; they are trying to attack the Syrian army’s positions, settlements and they are trying to threaten our military air base in Khmeimim.” A Syrian government assault on Idlib backed by Russian airpower and Special Forces would enhance the position of Damascus and Moscow in northern Syria at Turkey’s expense. TURKEY’S POSITION has been further compromised by the rapid reconciliation between the Assad regime and its Arab opponents, notably Egypt and the UAE. If Saudi Arabia follows suit, the anti-Turkey alignment led by Riyadh, Cairo and Abu Dhabi could mobilize most of the Arab nations against Ankara’s safe-zone plan, and given Damascus’ opposition to the plan, provoke the crystallization of a broader anti-Turkish Arab bloc.The Assad regime’s rehabilitation began with the December 16, 2018, visit to Damascus by Sudanese President Omar al-Bashir. This visit, the first by an Arab leader since Syria’s expulsion from the Arab League in 2011, signaled a wider thaw between Arab nations and the Assad regime, as it would not have occurred without Saudi approval. The visit also revealed the limits of Ankara’s influence over Sudan, despite Turkey’s $650 million of development initiatives. In a telling sign, the Sudanese president traveled to Damascus in a Russian plane. Sudan, cash-strapped and indebted to Russia, has reportedly given concessions to Russian companies in various extractive industries, including gold, diamonds, oil, and gas. Bashir’s Damascus visit was partially prompted by Moscow’s eagerness to bolster the Assad regime through renewed ties with the Arab world.A week later, Syria’s security chief Ali Mamlouk visited Cairo for talks reportedly at the invitation of Egypt’s intelligence chief. Subsequently, Ilham Ahmed, the co-chair of the SDF’s political arm, informed the press that the SDF’s Egyptian communication channels would be utilized in negotiations with the Assad regime to try to deter a Turkish intervention. Ahmed explained, “There have been contacts over the past few days between Kurdish leaders and Egyptian officials so that Cairo would take part in the mediation with Damascus.” Close military partners, Egypt and Russia are actively cooperating to combat Turkish-sponsored Islamist groups in Libya. According to Turkey’s pro-government newspaper Yeni Safak, Egyptian and UAE officials visited Manbij to discuss how to prevent a Turkish takeover. On December 27, 2018, the United Arab Emirates reopened its Damascus embassy after an eight-year hiatus. UAE Minister of State for Foreign Affairs Anwar Gargash explained in a tweet, “The Arab role in Syria is becoming more necessary toward Iranian and Turkish [efforts at] territorial change in the region. The UAE today, through its presence in Damascus, seeks to activate this role.” Six months earlier, Abu Dhabi and Moscow had signed a Declaration of Strategic Partnership. Hours after the UAE reopened its Damascus embassy, Bahrain restored its diplomatic mission. Algeria, opposed to Turkey’s support of Islamist militants in neighboring Libya, has been lobbying for Syria to be invited the March 2019 Arab League summit.Turkey cannot enter northeastern Syria without Russia’s tacit consent. The rapprochement between the Assad regime and Turkey’s major Arab rivals makes obtaining that consent more difficult, and risks Turkey’s Arab rivals supporting Kurdish forces in Syria, creating an intractable quagmire for Turkey with significant consequences for its own Kurdish region.Seeking to preserve Ankara’s tilt toward Moscow, the Kremlin has suggested Syrian government forces could establish Turkey’s proposed safe zone. During the Moscow January 23 meeting with Erdogan, Putin declared that the 1998 Adana Protocol between Ankara and Damascus was still operative. Under the agreement, Syria closed PKK bases on its territories, imprisoned PKK fighters, and expelled PKK head Abdullah Öcalan, resulting in his 1999 capture. Iran joined the protocol in 2003, and might support Russia’s proposal in order to limit cooperation between the Egypt-Saudi Arabia-UAE bloc and Damascus. At the next meeting of the Astana guarantors, Ankara may find itself forced to accept a Syrian-administered safe zone based on some updated understanding of the Adana Protocol.The writer is a Fellow at the Truman Research Institute for the Advancement of Peace at the Hebrew University of Jerusalem and an affiliated scholar with the Center for Strategic Studies at Baskent University in Ankara, Turkey (Baskent-SAM). Follow him @michaeltanchum. A longer version of this article originally appeared in The Turkey Analyst.