In the past two months, Syria's Eastern Ghouta has been shelled, bombed, attacked in ground assaults and it has now been allegedly hit by chemical weapons.

Key points: Eastern Ghouta was the rebels' major stronghold within striking distance of the capital

Eastern Ghouta was the rebels' major stronghold within striking distance of the capital Rebel attacks launched from the area have made reclaiming it a priority for the Syrian regime

Rebel attacks launched from the area have made reclaiming it a priority for the Syrian regime A chemical attack on Ghouta in 2013 killed 1,429 people, including 426 children

These attacks have killed almost 2,000 people — the majority civilians, including 371 children — according to the Syrian Observatory for Human Rights (SOHR).

As the US threatens retaliatory strikes against Syrian president Bashar al-Assad, key European nations have weighed in to condemn the chemical attack and offer a "strong and joint response" alongside the US.

With Syrian ally Russia warning of repercussions if the US acts, the impact of the strike on Eastern Ghouta could ripple well beyond Syrian borders.

So what is it about Eastern Ghouta that has made its population the victims of such frequent and vicious attacks?

Why Eastern Ghouta?

Map A map showing the area of Eastern Ghouta in relation to Damascus.

Ghouta is a semi-rural outer district of Syria's capital. It lies just 10 kilometres east of central Damascus.

After the Syrian conflict began as a revolution in 2011, rebels took control of a large section in the east of Ghouta in November 2012.

While other parts of Ghouta have fallen in and out of rebel hands, Eastern Ghouta has remained the rebels' major stronghold within striking distance of the capital.

The Syrian Government has frequently claimed rebels have launched shells and missiles into suburban areas of Damascus, making reclaiming the area crucial for the security of the city.

Civil defence members and civilians run from an air raid in eastern Ghouta. ( Reuters: Bassam Khabieh )

In February 2013, the Government began a siege on the area, blocking major supplies of food and medicine while frequently bombarding it from land and air.

Fighters and civilians alike living in Ghouta have since suffered starvation, epidemics, death and destruction.

The Ghouta region was previously home to about 2 million people, but thousands have been killed since the conflict began and hundreds of thousands have fled to other areas of Syria or internationally.

When the latest wave of attacks began in February 2018, the population of Eastern Ghouta was estimated to be just 400,000.

Local activists said this number included about 20,000 rebel fighters.

Not the first or worst chemical attack on Ghouta

The chemical attack on Ghouta on August 21, 2013 killed 1,429 people, including 426 children. ( Reuters: Bassam Khabieh )

In August 2012, then US President Barack Obama said in a press conference at the White House that the use of chemical weapons in Syria would be "a red line".

"That would change my calculus. That would change my equation," said Mr Obama who until then had stayed clear of direct involvement in the Syrian crisis.

One year later, rebel held areas of Ghouta were attacked by rockets containing sarin gas.

A US Government report put the death toll at 1,429, including 426 children.

International medical group Doctors Without Borders said a further 3,500 patients were treated for neurotoxic symptoms following the attack.

The Syrian Government and Russia at first denied the attack, but later claimed it was a false flag attempt by rebel forces to initiate an international strike against the regime.

Both a UN investigation team and the US Government concluded this scenario was extremely unlikely as rebel forces were not believed to have access to chemical weapons or the missiles used to launch them into Ghouta at this early stage of the conflict.

The red line was crossed, but Mr Obama refrained from action.

Instead a deal was brokered by Russia in which the Syrian Government were to hand over their chemical weapon stockpiles for destruction and join the Chemical Weapons Convention (CWC).

Aren't chemical weapon attacks in Syria common?

A medical worker giving toddlers oxygen through respirators following the alleged poison gas attack. ( Syrian Civil Defense White Helmets via AP )

Various groups have used chemical warfare in Syria on many occasions.

Reports of the use of phosphorus and chlorine gas as well as other unidentified chemical agents by the Syrian army against opposition forces have been frequent and often verified.

The Government has also claimed similar attacks by rebels and even some attacks have been reportedly launched during in-fighting between rebel groups.

But not all chemical agents fall under the CWC, which was created in 1993 in an effort to eliminate the production, stockpiling, and use of deadly chemical warfare.

Non-fatal chemicals such as teargas are frequently used for crowd control.

Phosphorus and chlorine, while often deadly, have largescale industrial uses and are therefore not regulated or monitored by the CWC.

But sarin gas is banned internationally which makes this particular attack on Eastern Ghouta — while nowhere near as deadly as the daily attacks by barrel bombs and missiles — a violation of the chemical weapons agreement brokered following the first attack on Ghouta.

When Mr Obama was weighing a response to the 2013 attack, Syria was not a signatory of the CWC.

Although the number of casualties of this recent attack pale in comparison to the first, Syria may now be in violation of a treaty they are signatories too and the agreement to destroy their chemical stockpiles.

The Syrian conflict has claimed more than 465,000 lives and displaced over 12 million Syrians.

The SOHR reported 40 deaths as a result of sarin gas in Eastern Ghouta last week.

While this single attack does seem insignificant in comparison to the average daily death toll, the consequences may be very significant for both the outcome of the Syrian conflict and international relations extending well beyond the Middle East.

Who are the rebels controlling Ghouta?

Sorry, this video has expired Video purports to show the remains of a missile dropped on Douma.

Various Syrian rebel groups have controlled parts of Ghouta over the years.

The main groups in control in recent months were Faylaq al-Rahman, belonging to the more moderate Free Syrian Army coalition, and extremist groups Ahrar al-Sham and Jaysh al-Islam — previously an Al Qaeda affiliate.

Following 10 days of bombardment that claimed about 600 lives with thousands more injured in February, civilians were offered a chance to flee Eastern Ghouta through a "humanitarian corridor", during a daily five-hour pause announced by Syrian ally Russia. But no-one left.

Russia claimed rebel groups were stopping civilians from fleeing, even shelling the corridor.

Civilians inside Ghouta said they were afraid to flee as there were no guarantees for their safety if they walked out into government-controlled areas.

Activist Osama Nassar, speaking to ABC by telephone from Eastern Ghouta at the time of the evacuation plan, said people did not trust the regime and feared arrest or forced military service if they fled into Government hands.

He described the impossible choice civilians like himself were facing.

"You either go to the torture centre or stay where you are starving and waiting the next barrel [bomb] to kill you or your kids," Mr Nassar said.

A new deal was brokered that would allow rebel fighters and civilians to travel by bus to rebel controlled Idlib province.

Most groups took the deal and much of the rebel enclave was shipped out in a convoy of buses.

But Jaysh al-Islam — an extremist group the Syrian regime and others have labelled as terrorists — still held Douma, the largest city in Eastern Ghouta.

While reportedly engaged in negotiations, they had not agreed to the final terms.

With the rebels on the brink of defeat, the alleged chemical attack seemingly handed the Government total victory in Ghouta.

Jaysh al-Islam released their regime prisoners and boarded buses for what civilians described as a harrowing 30-hour journey to rebel territory just 400 kilometres away.

Russia and the Syrian Government continue to deny there was a chemical attack at all.