For 29 months, Syrian President Bashar al-Assad's forces have been ruthlessly battling an anti-government uprising. Bombs and bullets have killed or maimed tens of thousands of Syrians. But it is a suspected poison gas attack that has really generated international outrage and set in motion a flurry of diplomatic wrangling, as the US seeks support for a limited military strike on the country.
The suspected chemical attack on August 21 has focused more attention on the Syrian conflict than any other single incident since the conflict began in March 2011, when activists, inspired by other popular uprisings across the Arab world, called for a 'Day of Rage'.
I am not sure it [the gas attack] could have been prevented by the West. If there had been more unanimity in the region perhaps it could have been stopped. But I think the Western democracies had very little influence because they were [in] deadlock … in the Security Council right from day one, because Russia and China took a very different view of this dispute … and it was very hard to see any way in which there could be a military invasion.
Assad tried to appease them, but by May, tanks and snipers had entered the southern city of Deraa and opened fire on protesters.
Some Syrian soldiers deserted, joining forces to form the Free Syrian Army in July, and both sides claimed gains in the year that followed.
On July 2012, the crisis escalated further. Assad's forces were accused of using fighter jets for the first time against rebel forces in Aleppo, and the US began to raise concerns about the use of chemical weapons.
In May, Hezbollah leader Hassan Nasrallah declared that fighters from Lebanon had joined forces with Assad's army.
But it was not until August this year, when a suspected gas attack killed hundreds in the Damascan suburb of Ghouta, that the current debate over military intervention began in earnest.
Assad has been talking on US television, repetitively denying responsibility for the alleged chemical attack.
"Our soldiers in another area were attacked chemically, our soldiers, they went to hospital as casualties because of chemical weapons. But in the area where they said the government used chemical weapons we only have video and we only have pictures and allegations," Assad said.
"We are not there. Our forces, our police, our institutions don't exist. How can you talk about what happened if you don't have evidences? We are not like the American admininstration, we are not the social media administration or government, we are the government that deals with reality," he added.
While John Kerry, the US secretary of state, has renewed US allegations that Syria's president launched the gas attack against his own people, speaking in the UK on Monday, he acknowledged that the conflict required a political solution.
For her part, the UN's human rights chief, Navi Pillay, said she first urged action to end the Syrian crisis nearly two years ago, when the death toll was less than 3,000. Now the number of dead tops 100,000.
"The international community is late, very late to take serious joint action to halt the downward spiral that has gripped Syria," she declared.
So, why has it taken a suspected chemical attack to bring demands for international military intervention in Syria? And what consequences could a military intervention have in the region?
To discuss this, Inside Story, with presenter Shiulie Ghosh, is joined by: David Owen, a former British foreign secretary and a former EU peace negotiator; General Mark Kimmitt, a former US state department official and retired brigadier; and Justin Crump, an international security and intelligence consultant.
"There is an opportunity for Bashar al-Assad to avoid the military strike ... [if he were to] forfeit his chemical weapons and then we can go to the negotiating table .... If he is not willing to give us his chemical weapons, to avoid the military strike, [it] is highly unlikely that he would answer the call of the G5 in the UN to [do] the same .... As Secretary Kerry said, military action is not the answer but may be the means to the answer .... If Bashar al-Assad is unwilling to give up his chemical weapons, if he is unwilling even to accept the fact that the world understands he has used them, then a red line has been crossed and there has to be serious consequences .... For [through] the use of these chemical weapons, he has violated an international norm that's been in place for many many years."
Mark Kimmitt, a former US state department official