One Year Ago: The Sarin Attack on Syria's Khan Sheikhun

Syrians dig a grave to bury the bodies of victims of a gas attack in Khan Sheikhun on April 5. (AFP)

A year ago a sarin gas attack on Syria's rebel-held town of Khan Sheikhun killed 83 according to the UN and 87 according to the Syrian Observatory for Human Rights.

The attack

On April 4, 2017 at around 7:00 am an air strike hits Khan Sheikhun, a small town in the northwestern province of Idlib.

Idlib is a stronghold of rebels opposed to regime leader Bashar al-Assad along with extremists implanted in the region.

Videos distributed by anti-regime activists show corpses lying in the streets, with others convulsing and suffering from suffocation.

Medical sources at the scene say patients suffer from symptoms such as fainting, vomiting and foaming at the mouth -- similar to those of previously recorded chemical weapons attacks.

Syria's opposition accuses Assad's regime of using munitions containing a toxic gas, a charge categorically denied by its forces.

According to the Britain-based Observatory it is the second worst chemical attack since the start of the war in 2011.

In 2013 more than 1,400 had died in a sarin gas attack in the Damascus suburbs.

Trump strikes

Overnight on April 7, on the orders of President Donald Trump, the US military fires 59 Tomahawk missiles from warships in the Mediterranean at the central Shayrat airbase, near the central city of Homs.

According to the Pentagon, US intelligence have established that the base was the launchpad for the chemical attack.

The Syrian regime describes the US strike as "foolish and irresponsible". Assad's ally Moscow calls it an "aggression against a sovereign state". Days later it vetoes a draft resolution at the UN Security Council.

Assad says the West "fabricated the whole story in order to have a pretext for the attack".

UN blames the regime

On June 29, the Organization for the Prohibition of Chemical Weapons (OPCW) says sarin gas was used in the attack, without saying who was responsible.

On October 26, a joint UN-OPCW panel says it is confident the Syrian regime is responsible, in conclusions rejected by Moscow.

On November 8, the US, Britain, France and Germany, say a presumed chemical attack which just preceded that in Khan Sheikhun "bears the hallmarks of the Syrian regime".

On November 16-17, Russia vetoes on two occasions renewal by the UN Security Council of the mandate of the UN-OPCW investigation.