Victims of gas attacks in Syria (picture by CNN)

The report of the UN envoys in Syria who were in charge of looking for evidence that Assad used chemical weapons on 21 August documents "the most significant gas attack on civilians since 1998, when Saddam Hussein used them in Halabja”, as stated by UN Secretary-General Ban- Ki moon.

The attack was almost certainly carried out by the Syrian regime, although the inspectors did not write it down in the report - in fact their mandates was limited to demanding an inquiry on what happened and did not include the task of finding the culprit. Although it remains theoretically possible that some missiles were smuggled by the rebels to provoke a US retaliation, the details of the 41-page report presented to Ban Ki-Moon, that document the type of ammunition used, the quantity and quality of sarin gas, the broad extent of the assault and the missile trajectory seem to point surely to Assad's responsibilities.
Only Russia pulls the brake, demanding more scientific investigation, but the writings in cyrillic alphabet found on the missiles deployed in the assault, which lead to think of Russian aid to Assad, as a matter of fact cannot but embarrass the Kremlin.
The 21 August attack in the outskirts of Damascus seems to have been carried out with ground missiles transporting 350 litres of sarin gas. The trajectory of the rockets is very significant, as it shows that all vectors came from areas firmly held by Assad's forces. The bombing was carried out by night, when the temperature significantly lowers and enables gas to remain firmly gripped to the ground and spread into the underground, where civilians hide from the attacks. 
The inspectors, run by the Swedish expert of chemical weapons Ake Sellstrom, also observed the wounds of the attack on 80 survivors: suffocating syndrome, convulsions, nausea, spasms, excess salivation, loss of the sense of direction, shrunk pupils, blurry sight, extreme fatigue, uncontrolled tremor and faints. The very doctors who had given first aid to the victims felt sick. 
Shocking testimonies include that of a child who lost 26 relatives to the attack, as remembers Maurizio Barbeschi, Italian member of the inspectors team. "He had remained alone. I will never forget about him. It is true that there had already been 100 thousand casualties of war, and we cannot list a parade of atrocities. But chemical weapons make it all impossible to describe in words”.
Ban Ki- moon said that now it is up to others to ascertain the responsibilities for the attack, but he went on saying: "This is a war crime and a gross violation of international law. I trust that everybody will join me in condemning this contemptible crime. The international community must ensure that the guilty are handed to justice”. It is now up to the Security Council to decide the way this must be done.