Syria has now been embroiled in a brutal civil war for four and a half years. The conflict has morphed into a proxy war as various powers compete for influence on the ground and seek to use Syria to further their larger foreign policy aims. The country is entirely fractured. The only way to end this morass of death and destruction is a negotiated settlement that grants some of the demands of the major factions while also taking into account the interests of the major foreign powers intervening in the conflict.

There are four main groups of combatants. First, the Assad regime itself, which controls many of the country’s population centers as well as Syria’s coastal strip — a large chunk of territory in the country’s west that has always been Syria’s heartland. Dominated by the Alawite minority, a Muslim sect related to the Shi’a but with syncretic elements, these regions have stayed loyal to the Assad government throughout the war or have been won back by the regime over the past few years, as in the case of the city of Homs, which was under Assad control from May 2011 through last year. The regime holds about a quarter of the country. A second group is the so-called moderate opposition — an umbrella term for a number of different rebel groups, mostly Sunni, with ideologies ranging from republican to radical Islamist. These groups control the Idlib province in the north, as well as a stretch of territory in the south along the border with Israel and Jordan and scattered pockets of resistance throughout Syria. This notably includes a large part of the Damascus suburbs, which has been under government siege for years.

The next two pieces in this jigsaw puzzle are the Kurdish regions and the Islamic State. The Kurds, a major ethnic group that spans Turkey, Iraq, Iran and Syria but is without a state, have used the chaos of the civil war to seize control of the Kurdish-populated regions of the north. The Kurds now control most of the territory along Syria’s northern border and have recently launched successful offensives that resulted in more territorial gain in the north from the Islamic State. The Islamic State, which has come into prominence in the past year and a half, now controls most of northern and eastern Syria, where it has established a jihadist state ruled by a self-declared caliph. The Islamic State’s rapid rise shocked the world, and the group’s radical ideology and uncompromising goals represent a major threat to the rest of Syria. As of now, the country is too divided to take back the roughly half of its territory now under Islamic State control.

A negotiated solution is the only way to mitigate this maelstrom. The country is too fractured; no one faction has the strength the fully defeat the others. Each side’s continued attacks and counterattacks could continue indefinitely if peace is not achieved. A June U.N. estimate put the number of casualties between about 230,000 and 320,000, and many more have disappeared; it is impossible to be sure of the final tally, though we can be sure it is astronomical. Furthermore, the conflict contributed to the flight of four million refugees leaving the country and another seven million internally displaced Syrians. To put these numbers in perspective, Palestinian refugees in 1948 numbered 726,000 to 957,000, an exodus which still reverberates around the Middle East.

Foreign intervention is another reason the conflict seems to have no military solution. The Assad regime is receiving huge amounts of aid from both Russia and Iran, while Israel, Saudi Arabia, Turkey, the United States and other countries each support factions of the opposition. The rebels effectively morphed into a variety of different groups, including armed militias national and Hezbollah, a Shi’a group from Lebanon that has elements of a political party, a state and an army. The Assad regime is dependant on the support of its core regions, as well as Iran and Russia, to survive. Assad’s foreign backers are committed to keeping the regime from collapse, and Russia is asserting itself in the Middle East in a way it has not done since the Cold War.

The Syrian state has effectively collapsed, as no institution can hold complete influence throughout the country. Therefore, the international community must mediate a deal between the regime, the rebels and the Kurds to stop the slaughter and contain the Islamic State. This agreement would have to suit not only the warring factions but also foreign powers involved in the war. This means preserving the Assad government in some form, while also granting the rebel and Kurdish provinces autonomy. Although it seems abhorrent to perpetuate a regime that has slaughtered its own people, this is an outcome preferable to endless civil war. A conceivable solution might involve Bashar al-Assad himself stepping down, while his Alawite-dominated government remains intact. In turn, the non-Islamic State regions that have slipped out of government control in the northwest and southwest of the country, as well as the Kurdish regions along the northern border, would have full self-government while slowly being reintegrated economically into the rest of the country. This way, Iran and Russia will be able to preserve their influence while the groups supported by the opposition’s backers survive. One could hope that once peace had been achieved in the rest of the country, the Islamic State could be driven out of the regions it currently occupies. A reconciliation between the country’s warring factions seems unlikely at present, but some form of agreement is the only way to end the war short of a total victory by one side — or the permanent breakup of Syria.