The SDF is potentially the player most affected by this decision, since it is losing a guarantor that protected it from any attackers vying for its areas of control.

President Donald Trump’s sudden announcement Dec. 19 that he will withdraw US soldiers from Syria has shuffled the cards and raised several questions about potential changes in the military map of control and the political balance of power in Syria following the withdrawal.

The Syrian regime reported early Friday that its troops had entered Manbij, though subsequent accounts from the United States said Syrian fighters had not yet entered the city. Other late reports said regime forces had established a barrier between the city and nearby Turkish troops.

Syria amassed its troops at Manbij in northern Syria, near the Turkish border — a city Turkey has been threatening to attack for more than a year, and with increasing frequency of late. Manbij is currently occupied by US troops and the US-supported Syrian Democratic Forces (SDF). The SDF is an alliance of primarily Kurdish and Arab militias that have helped the United States fight the Islamic State (IS).

JARABLUS, Syria — As the many parties invested in Syria were considering how they might be affected by the United States withdrawing its troops , the Syrian regime made its own move Friday.

However, it's harder to categorize the Syrian opposition as winners or losers as a result of the US withdrawal. The repercussions of the decision need to be carefully studied in many respects.

The United States has been a political supporter of the opposition’s quest to oust Syrian President Bashar al-Assad. This effort won't be affected by the US troop withdrawal, according to Yasser Farhan, a member of the political committee of the Syrian National Coalition, formally known as Etilaf, the National Coalition of Syrian Revolution and Opposition Forces.

“America’s power can't be reduced to the 2,130 soldiers deployed on Syrian territory,” Farhan told Al-Monitor. “Americans have several means to help the Syrian people and to reach a political solution if they want to. They can simply show their seriousness through political pressure on the regime, pushing it to respond to international resolutions. This alone is enough to solve the problem in Syria."

Syrian opposition factions are waiting for an opportunity to participate in Turkey's planned military operation east of the Euphrates, though Turkish President Recep Tayyip Erdogan postponed the action Dec. 21.

The opposition wants more geographical control on the ground; it currently controls about 10% of Syria's total area.

Maj. Youssef al-Hamoud, spokesman for the opposition's Syrian National Army, which has Turkey's backing, believes the withdrawal of US troops will be benefit the opposition.

“The Syrian National Army, along with the Turkish army, will enter all the areas from which the US withdraws and will liberate them from the terrorist forces of the PKK [Kurdistan Workers Party] and PYD [the US-supported, Kurdish nationalist Democratic Union Party],” he told Al-Monitor. Turkey considers both groups to be terrorist organizations.

In a tweet Dec. 23, Trump said he had a “long and productive” phone call with Turkish President Recep Tayyip Erdogan in which they discussed “a slow & highly coordinated pullout of US troops" from Syria. Initially Trump had called for a "full" and "rapid" withdrawal.

Hamoud said that Turkey's increasing role in Syria gives the Syrian National Army more strength because Ankara is the only party still supporting the Syrian revolution "in all its forms, be it political, military or relief."

The Syrian rebels hope the US withdrawal will speed up their movement east of the Euphrates, but at the same time, they fear losing the strategic al-Tanf area at the Syrian-Jordanian-Iraqi border triangle. This is where opposition fighters are deployed under the umbrella of the US-led international coalition against IS. The United States has a military base near al-Tanf crossing on the highway connecting Baghdad to Damascus. The Syrian regime and Iranian-backed militias have been repeatedly attacked by the coalition whenever they get near the area.

Iran seeks to control the area to secure arms transfers to Hezbollah members near Damascus and Lebanon. “Just as it offers us a range of opportunities, the US withdrawal also places us in the face of several threats,” Farhan said.

Farhan believes the United States can still stop the Iranian expansion, even after withdrawing its troops.

“The US has aircraft and missile weapons. When it wants to block the Iranian tide, it can do so without troops on the ground. It is enough to have the support" of the Free Syrian Army, which is affiliated with the Syrian National Army. The Free Syrian Army "will take it upon itself to ward off Iran from Syria and the entire region,” he said.

As mentioned, the US withdrawal will allow Turkish forces and the Syrian opposition to move east of the Euphrates. But it will also open the door for Iran and Russia, which support Assad, to interfere in the oil- and gas-rich area that is considered Syria’s food basket.

Ankara's declared goal for its "east of the Euphrates" operation is to eliminate SDF, which it sees as a threat to its national security. The pertinent question, however, is: Why would Turkey mind Iran and Russia intervening if this would achieve the same goal?

Turkey is trying to avoid a clash with Russia and Iran and gain more approval from them to keep the cease-fire standing in rebel-held Idlib, to proceed with forming the Syrian Constitutional Committee and most importantly to prevent a deal between the Syrian regime and the SDF — which looks to be happening now. The SDF wants to avoid losing its areas of control to the Turks and the Syrian opposition.

The Syrian regime retains control over the Qamishli airport and two security squares in the cities of Hasakah and Qamishli in northeast Syria. SDF controls the entire surrounding area.

The security squares house government and security buildings and offices. Hundreds of citizens from the city of Qamishli took to the street Dec. 23, condemning Turkey's intervention in the country and calling for regime forces to protect their areas. Should this scenario play out, it would pose a real threat to the Syrian opposition, which sees Assad’s regime as its main enemy.

The Kurds, on the other hand, “don't have a problem with the regime," SDF spokeswoman Jihan Ahmad said in a press statement Dec. 21. "Negotiating teams representing the Syrian Democratic Council [SDC, the SDF's political wing] have sat on several occasions with representatives of the regime.”

In tandem with the diplomatic efforts, SDF has sent military reinforcements to the Syrian-Turkish border, digging trenches and setting up barricades in anticipation of a possible Turkish offensive.

“We are part of Syria and we are not advocates of separation. We, however, wish to have an agreement on self-management of our own affairs,” she added.

Perhaps lost among all these conflicting interests and objectives is one party that's of no small concern.

IS might find an outlet to try to expand once more.

IS still controls 2% of Syrian territory in two strongholds in Deir ez-Zor governorate: one within a regime-controlled area, and another pocket inside an SDF-held area. This year, US Defense Department and UN estimates pegged active IS fighters in Syria at 20,000 to 31,600. In 2015, at the height of IS' power, US intelligence estimated the group had 33,000 fighters in Syria and Iraq. This leaves many observers fearing that IS could use its expertise in guerrilla tactics to expand from the desert areas it controls.