WHAT BEGAN AS PEACEFUL UPRISING AGAINST SYRIA'S PRESIDENT BASHAR AL-ASSAD SIX YEARS AGO BECAME A FULL-SCALE CIVIL WAR THAT HAS LEFT MORE THAN 300,000 PEOPLE DEAD,DEVASTATED THE COUNTRY AND DRAWN IN GLOBAL POWERS.


HOW DID THE WAR BEGAN?
LONG BEFORE THE CONFLICT BEGAN,MANY SYRIANS COMPLAINED ABOUT HIGH UNEMPLOYMENT,WIDESPREAD CORRUPTION,LACK OF POLITICAL FREEDOM AND STATE REPRESSION UNDER PRESIDENT BASHAR AL-ASSAD,WHO SUCCEEDED HIS FATHER,HAFEZ,IN 2000.
IN MARCH 2011,PRO-DEMOCRACY DEMONSTRATIONS INSPIRED BY THE ARAB SPRING ERUPTED IN THE SOUTHERN CITY OF DERAA.THE GOVERNMENT USE OF DEADLY FORCE TO CRUSH THE DISSENT SOON TRIGGERED NATIONWIDE PROTESTS DEMANDING THE PRESIDENT'S RESIGNATION.
AS THE UNREST SPREAD,THE CRACKDOWN INTENSIFIED.OPPOSITION SUPPORTERS BEGAN TO TAKE UP ARMS,FIRST TO DEFEND THEMSELVES AND LATER TO EXPEL SECURITY FORCES FROM THEIR LOCAL AREAS.MR.ASSAD VOWED TO CRUSH ''FOREIGN-BACKED TERRORISM''AND RESTORE STATE CONTROL.
THE VIOLENCE RAPIDLY ESCALATED AND THE COUNTRY DESCENDED INTO CIVIL WAR AS HUNDREDS OF REBEL BRIGADES WERE FORMED TO BATTLE GOVERNMENT FORCES FOR CONTROL OF THE COUNTRY.



WHY HAS THE WAR LASTED SO LONG?
A KEY FACTOR HAS BEEN THE INTERVENTION OF REGIONAL AND WORLD POWERS,INCLUDING IRAN,RUSSIA,SAUDI ARABIA AND THE UNITED STATES.
THEIR MILITARY,FINANCIAL AND POLITICAL SUPPORT FOR THE GOVERNMENT AND OPPOSITION HAS CONTRIBUTED DIRECTLY TO THE INTENSIFICATION AND CONTRIBUTION OF THE FIGHTING,AND TURNED SYRIA INTO A PROXY BATTLE GROUND.
EXTERNAL POWERS HAVE ALSO BEEN ACCUSED OF FOSTERING SECTARIANISM IN WHAT WAS A BROADLY SECULAR STATE,PITCHING THE COUNTRY'S SUNNI MAJORITY AGAINST THE PRESIDENT'S SHIA ALAWITE SECT.SUCH DIVISIONS HAVE ENCOURAGED BOTH SIDES TO COMMIT ATROCITIES THAT HAVE NOT ONLY CAUSED LOSS OF LIFE BUT ALSO TORN APART COMMUNITIES,HARDENED POSITIONS AND DIMMED HOPES FOR A POLITICAL SETTLEMENT.


WHY ARE SO MANY OUTSIDE POWERS INVOLVED?
RUSSIA,FOR WHOM PRESIDENT ASSAD'S SURVIVAL IS CRITICAL TO MAINTAINING ITS INTERESTS IN SYRIA,LAUNCHED AN AIR CAMPAIGN IN SEPTEMBER 2015.WITH THE AIM OF ''STABILISING THE GOVERNMENT AFTER SERIES OF DEFEATS.MOSCOW STRESSED THAT IT WOULD TARGET ONLY ''TERRORISTS'' BUT ACTIVISTS SAID ITS STRIKES MAINLY HIT WESTERN-BACKED REBEL GROUPS.
SIX MONTHS LATER,HAVING TURNED THE TIDE OF WAR IN HIS ALLY'S FAVOUR,PRESIDENT VLADIMIR PUTIN ORDERED THE ''MAIN PART'' OF RUSSIA'S FORCES TO WITHDRAW,SAYING THEIR MISSION HAD ''ON THE WHOLE'' BEEN ACCOMPLISHED.
HOWEVER,INTENSE RUSSIAN AIR AND MISSILE STRIKES WENT TO PLAY A MAJOR ROLE IN THE GOVERNMENT'S SIEGE OF REBEL-HELD EASTERN ALLEPO,WHICH FELL IN DECEMBER 2016.
THE U.S.,WHICH SAYS PRESIDENT ASSAD IS RESPONSIBLE FOR WIDESPREAD ATROCITIES,HAS PROVIDED ONLY LIMITED MILITARY ASSISTANCE TO ''MODERATE'' REBEL GROUPS,FEARFUL THAT ADVANCED WEAPONS MIGHT END UP IN THE HANDS OF JIHADISTS.THE U.S. HAS CONDUCTED AIRSTRIKES ON IS IN SYRIA SINCE SEPTEMBER 2014,AND,IN THE FIRST INTENTIONAL ATTACK ON SYRIA ITSELF,HIT AN AIR BASE WHICH IT SAID WAS BEHIND A DEADLY CHEMICAL ATTACK,IN APRIL 2017.



WHAT IMPACT HAS THE WAR HAD?
THE UN,SAYS AT LEAST 250,000 PEOPLE HAVE BEEN KILLED IN THE PAST FIVE YEARS.
HOWEVER,THE ORGANISATION STOPPED UPDATING ITS FIGURES IN AUGUST 2015.THE SYRIAN OBSERVATORY FOR HUMAN RIGHTS,A UK-BASED MONITORING GROUP,PUTS THE DEATH TOLL AT MORE THAN 321,000,WHILE A THINK-TANK ESTIMATED IN FEBRUARY 2016 THAT THE CONFLICT HAD CAUSED 470,000 DEATHS,EITHER DIRECTLY OR INDIRECTLY.
FIVE MILLION PEOPLE-MOST OF THEM WOMEN AND CHILDREN-HAVE FLED SYRIA,ACCORDING TO THE UN.NEIGHBORING LEBANON,JORDAN AND TURKEY HAVE STRUGGLED TO COPE WITH ONE OF THE LARGEST REFUGEE EXODUSES IN RECENT HISTORY.
ABOUT 10% OF SYRIAN REFUGEES HAVE SOUGHT SAFELY IN EUROPE,SOWING POLITICAL DIVISIONS AS IN COUNTRIES ARGUE OVER SHARING THE BURDEN.A FURTHER 6.3 MILLION PEOPLE AS INTERNALLY DISPLACED INSIDE SYRIA.
THE UN ESTIMATES IT WILL NEED $3.4 BILLION [2.7 BILLION POUNDS] TO HELP THE 13.5 MILLION PEOPLE WHO WILL REQUIRE SOME FORM OF HUMANITARIAN ASSISTANCE INSIDE SYRIA IN 2017.
ALMOST 85% OF SYRIANS LIVE IN POVERTY,WITH MORE THAN TWO-THIRDS OF THE POPULATION IN EITHER EXTREME OR ABJECT POVERTY.
MORE THAN 12.8 MILLION PEOPLE IN SYRIA REQUIRE HEALTH ASSISTANCE AND MORE THAN SEVEN MILLION ARE FOOD INSECURE AMID RISING PRICES AND FOOD SHORTAGES.HOUSE HOLDS SPEND UP TO A QUARTER OF THEIR INCOME JUST ON WATER.SOME 1.75 MILLION CHILDREN ARE OUT OF SCHOOL.
THE WARRING PARTIES HAVE COMPOUNDED THE PROBLEMS BY REFUSING HUMANITARIAN AGENCIES ACCESS TO MANY OF THOSE IN NEED.SOME 4.9 MILLION PEOPLE LIVE IN BESIEGED OR HARD-TO -REACH AREAS.