Previously, former US President Barack Obama had said that the use of chemical weapons would cross a “red line”, but failed to follow through.

After the Khan Sheikhoun attack, the US had said that Syrian President Bashar al-Assad must be held accountable.

The UN report also found that the government forces were responsible for at least 23 other chemical attacks in the war-ravaged country since March 2013, in areas including the provinces of Idlib, Hama and eastern Ghouta.

At the time, UN investigators said they had found no evidence supporting Syrian and Russian claims that the chemicals had been released when an air raid hit an opposition weapons depot in the area, producing chemical munitions.

“Our voices on the ground are not being heard or acknowledged by the international community because that community is only interested in their own state affairs,” Abdulnoor, the activist, said.

“These investigations purposefully take a long time to reveal what is in fact already obviously true. If they [international community] wanted to hold Assad accountable, the investigation would have been concluded in a day,” he said.

“As long as the war continues to serve their agendas, these investigations will never change things on the ground,” he added.

Mazen Kewara, a Turkey-based surgeon with the Syrian American Medical Society (SAMS), explained that the international community cannot take action when such investigations are conducted for several reasons, rendering them obsolete.

“We [SAMS] provided OPCW with testimonies from doctors, wounded civilians, witnesses, and footage from Syria to help them reveal details behind several attacks,” said Kewara, who is based in the Turkish border city of Gaziantep.

“The reason these investigations take time is because they have a complex mechanism and protocol. The OPCW, in particular, is an autonomous body that works discretely,” he explained.

According to Kewara, several UN resolutions against the Syrian regime have been stalled by veto-wielding members of the Security Council.

“The main problem here is Russia and China’s support – these are delaying and preventing the international community from taking punitive measures against Assad’s regime,” he said.

Moscow has vetoed UNSC resolutions against Syria seven times in the past five years, particularly resolutions that threatened sanctions against parties using chemical weapons in Syria.

A report on OPCW’s investigation will be available to the body’s member states and to the OPCW-UN joint investigative committee within few weeks.

Now in its seventh year, the Syrian civil war has killed nearly half a million Syrians, injured more than a million, and displaced over 12 million people from their homes.