US ULTIMATUM TO MOSCOW

Author: Rex Tillerson, US Secretary of State

“Moscow must think about whether to remain an ally with the Assad regime, the Iranians and Hezbollah. Is that a long term alliance that serves Russia's interests? Or would Russia prefer to realign with the United States, with other Western countries and Middle East countries that are seeking to resolve the Syrian crisis? Russian-brokered talks in Astana have not produced much progress, and a process underway in Geneva over Syria's political future would be fruitful. Bashar al-Assad will not be part of that future. In terms of the future of Bashar al-Assad, it is important to us that we undertake a political process that leads to the final conclusion of how Syria will be governed. It is our policy for a unified Syria that is governed by the people of Syria. I think it is clear to all of us that the reign of the Assad family is coming to an end."

Key Actors in the Conflict

Regime and Allies: The Syrian army's 300,000-strong pre-war force has been halved by deaths, defections and draft-dodging. It is bolstered by 150,000-200,000 irregulars and supported by 5,000-8,000 men from Lebanon's Shiite militia Hezbollah, as well as Iranian, Iraqi and Afghan fighters. Key regime backer Russia began an air campaign in support of President Bashar al-Assad in September 2015 and has helped Damascus recapture several key areas, including Aleppo city. Iran has also provided major financial and military support to Assad. The government controls around 34 percent of Syria's territory, including key cities such as Damascus and second city Aleppo. Of the 16 million Syrians who remain in the country, 65.5 percent live in regime territory.

Rebels: Syria's opposition comprises a wide range of factions, including moderate rebels and Islamist groups. Estimates of its total number of forces range from tens of thousands up to around 100,000. Early on, rebels coalesced under the banner of the Free Syrian Army (FSA), but the opposition has since splintered. The most powerful is Ahrar al-Sham, which espouses a hardline Islamist ideology and boasts a commanding presence in Idlib and Aleppo provinces. Another key opposition group is the Saudi-backed Jaish al-Islam (Army of Islam), whose leading member Mohammad Alloush has led previous delegations to both Geneva and parallel talks in Astana. Rebels now hold only around 13 percent of the country, including areas where they are allied with Fateh al-Sham. Around 12.5 percent of Syria's remaining population lives in rebel-held territory.

Jihadists: There are two rival jihadist forces: the Islamic State group and former Al-Qaeda affiliate Fateh al-Sham Front. IS emerged from the chaos of the war to seize control of large parts of Syria and Iraq in mid-2014, declaring an Islamic "caliphate", committing widespread atrocities and carrying out or inspiring deadly attacks abroad. Under pressure from an air war launched two years ago by a US-led coalition and fighting on multiple fronts, IS has suffered major losses. But it still holds 33 percent of Syrian territory, including its de facto capital Raqa, ancient desert city Palmyra and Al-Bab in northern Syria. Fateh al-Sham Front split in July 2016 from Al-Qaeda in a move that was aimed at easing pressure from both Moscow and the US-led coalition which have regularly targeted its forces with air strikes. Fateh al-Sham had been closely allied with Ahrar al-Sham since 2015, but infighting broke out between the two factions in January. Rebel groups were forced to ally with either Ahrar or Fateh al-Sham, which rebranded itself again into Tahrir al-Sham.

The Kurds: Syria's Kurds have largely stayed out of the conflict between the government and armed opposition, carving out a semi-autonomous region in north and northeastern Syria. Their People's Protection Units (YPG) have become a key partner of the US-led coalition fighting IS as part of the Kurdish-Arab Syrian Democratic Forces (SDF). The YPG controls about 20 percent of Syrian territory but as much as three-quarters of the northern border with Turkey. Two million people, around 12.5 percent of Syria's remaining population, live in Kurdish-held territory. The SDF has launched a drawn-out offensive against IS's stronghold in Raqa. Turkey began an offensive into Syria in August 2016 against IS and the YPG, which Ankara regards as the Syrian branch of the Kurdistan Workers' Party (PKK) that has waged a 32-year insurrection inside Turkey.

Turkey, Saudi Arabia, Qatar: Sunni-majority Saudi Arabia, Qatar and Turkey have provided military and financial support to rebels fighting Assad, who belongs to the minority Alawite community linked to Shiite Islam. Long accused of turning a blind eye to jihadist activity along its southern border, Turkey has joined the US-led coalition fighting IS and has deployed troops to fight the group in northern Syria. Although they support opposing sides of the war, Ankara and Moscow have worked closely in recent months to secure a political solution to the conflict. They brokered a fragile ceasefire between rebels and regime forces in December 2016 and hosted talks on reinforcing the truce and other confidence-building measures in Kazakhstan

International Coalition: A US-led coalition has carried out air strikes against IS and other jihadists in Syria since 2014. The coalition's members include Australia, Bahrain, Britain, Canada, France, Jordan, the Netherlands, Saudi Arabia, Turkey and the United Arab Emirates.