A brief history of the Syrian War
In March 2011, a teenager spray painted a wall in the Syrian city of Da'raa.
"It's your turn doctor," the text read.
The vandal was referring the the country's president, Bashar al Assad, a British-trained ophthalmologist. It was his 'turn' to lose power in the Arab Spring, a wave of uprisings spreading across the Middle East.
In response, the Syrian government rounded up more than a dozen children - as young as 10, some say - and held and tortured them for weeks to find out who was responsible.
The act came to symbolise the repressive and often brutal rule of the country’s leader, Bashar al Assad, sparking protests from relatives, neighbours and hundreds of others in Da'raa.
When Syrian security forces opened fire on the crowds protesting the government's actions, events escalated quickly. The government’s crackdown only led to more unrest, radicalising citizens who formed rebel groups to fight the government.
That was the start of a brutal, messy civil war which has since killed hundreds of thousands of people, caused millions more to flee, and contributed to the rise of Islamist terror groups such as Islamic State.
One of the most prominent of the early groups fighting against the government was the Free Syrian Army. They were a group led by several former army officers and formed several months after the initial protests.
The main opposition group at the time, representatives said they were a secular group committed to bringing democracy to Syria.
After several years of war, the "army" wing of the Free Syrian Army has all but fallen apart. It's now more of a loose group of rebel militias fighting under the same banner and sharing some resources.
Those groups aren't the only ones on the ground, there are many other rebel forces, ranging from moderate fighters to hardline Islamists.
Several significant groups, such as IS, are fighting to establish an Islamic theocracy.
To complicate things further, many of those forces are not only fighting against Assad, but also against each other.
Then there's another player, the Kurdish forces.
Around 30 million Kurdish people also live in the region which straddles the borders of Turkey, Iraq, Syria, Iran and Armenia.
For over 100 years, the group has aspired to form their own state, and in the wake of the instability, Kurdish groups have been fighting to retain control of their territory.
Human rights groups have reported widespread atrocities committed by all parties, including the use of child soldiers.
The UN has condemned the government, Islamist groups and rebel forces for indiscriminate attacks, arbitrary arrests and torture.
Russian and government forces, in particular, have been singled out for condemnation for the use of chlorine gas and cluster munitions in civilian areas.
Because of Syria’s size, location, and air and sea access routes, the country is of high strategic importance.
Friendly with the Assad regime, Iran has sent fighters to assist. Hezbollah in neighbouring Lebanon is also fighting for Assad.
In September 2015 Russia carried out its first air strikes in support of Assad, and has now become an active ally in the regime's military campaign.
President Obama was harshly criticised for keeping the US from becoming too involved in the conflict, but as Islamist fighters spilled into Iraq, the Obama administration was drawn in.
‘Military advisors’ have been supporting Iraqi forces and the US has been leading a coalition of forces – including Australia – which has been bombing Islamist targets.
Following a request from President Obama in 2015, the Australian government joined the United States and other coalition partners in bombing raids against IS in Syria.
Roughly 780 Australian Defence Force Personel are deployed in the region, supporting the expanded operation based in Iraq.
With the election of President Trump in 2016, the United States appeared to be on course for a change in policy.
President Trump had criticised Obama for being “weak” on Syria by not attacking IS aggressively, and had previously urged the president not to launch any military attack on the Syrian government.
Under President Trump, White House initially said it would direct efforts towards fighting IS and described Assad’s position as president as a “political reality” which needed to be accepted.
However, in April, the administration sharply reversed its course.
After a suspected Sarin attack which killed numerous children in the town of Khan Sheikhun, President Trump ordered America's first ever military strike in the conflict - a strike on the Syrian government airbase from where the United States suspected it had launched the chemical attack.
The Trump Administration has since said it no longer sees a solution to the conflict in which President Assad remains in power.
While operating in the same region for opposing sides, Russia and the United States have adopted so-called "deconfliction" protocols to avoid direct clashes as they operate overlapping military campaigns.
Russia threatened to suspend this process after the US strike on Khan Sheikhun, and it's unclear if the agreement remains in operation.
Saudi Arabia and Qatar – rivals of Iran – want Assad gone and have been providing military and financial assistance to rebel groups, including some of the Islamist forces.
They are also bombing other Islamist forces – such as Islamic State – as part of the US-led campaign.
Neighbouring Turkey isn’t a fan of IS, and they’ve been attacking the group for several years. Turkey has in the past called for the removal of Assad.
Turkey is also strongly opposed to a group who would otherwise be their allies in their fight, the Kurds.
Kurdish separatists in Turkey’s east have been fighting for independence for years, including bomb attacks. Turkey fears that gains by Syrian Kurds will support and embolden Kurdish groups at home.
So, as well as attacking IS, Turkey has also been attacking Kurdish forces.
The Syrian civil war has escalated beyond what anyone could have imagined when the government arrested those teenagers in 2011.
The fighting has killed more than 400,000 people, according to the United Nations, with almost 5 million forced to flee the country. Millions more remain internally displaced within Syria.
Human rights abuses are serious and widespread, according to rights groups.
Human Rights Watch says that armed groups are mounting deliberate and indiscriminate attacks on civilians, using child soldiers, and torturing prisoners.
The government is guilty of disappearances, torture, arbitrary arrest, and allowing numerous deaths in custody, they say.
In 2013, hundreds of people were killed – including many children – in a poison gas attack on civilian neighbourhoods in Damascus. An attack which Western governments say was almost definitely carried out by the Assad regime.
The government stands accused of repeatedly using chlorine, sarin gas and barrel bombs on its own civilians.
In the recent battle for the rebel stronghold of Aleppo, the UN raised concerns of widespread war crimes on all sides - including indiscriminate targeting, government use of chemical weapons and rebel use of human shields.
The humanitarian fallout has also had a significant impact on surrounding countries, with Lebanon now home to over one million Syrian refugees – who make up as much as 20 per cent of the country's current population.
Using its control of regions of Syria and Iraq as a base, IS has spread its propaganda and violence around the world.
From beheadings and mass executions in Iraq and Syria, to attacks on tourist beaches in Tunisia, crowded events in Europe and a gay bar in Florida – the group has used the conflict to spread death, hate and fear around the world.
The crisis has generated hundreds of thousands of official asylum applications in the European Union, while thousands more attempt to reach Europe by land and by sea.
The EU migrant crisis has become major challenge for the open-border political union, with migration said to be a major driver of last year's Brexit vote and the rise of right-wing parties in Germany and France.
What started with protests in Da'raa has now become a sprawling conflict with global ramifications.
Nobody really knows when or how the crisis will end. The war has been raging for over six years now, and there is yet to be any dominant ‘winner’.
With such an array of different armed groups on the ground, it's difficult to see any single group gaining the upper hand and ending the conflict through military strength.
That’s why many see a negotiated political solution as the only realistic outcome.
But with so many divergent groups and so many external vested interests, getting everyone to the table and keeping them there is proving difficult – especially with both government and rebel forces convinced they can strengthen their hands through wins on the battlefield.