According to the leading international organization that tracks these weapons, more than 100 chemical weapons sites have been suspected of staying in Syria after the collapse of long-time President Bashar al-Assad.
The figure is the first estimate of the group that the banned chemical weapons organization attempted to enter Syria to assess the remains of Mr. Al-Assad's infamous military plan. The figure is much higher than any figure recognized by Mr. Al-Assad.
These sites are suspected to be involved in the research, manufacturing and storage of chemical weapons. During more than a decade of civil war, Mr. Al-Assad used weapons such as sarin and chlorine to counter rebel fighters and Syrian civilians.
The number of the site and whether it is protected has been a mystery since the rebels overthrew Mr. Al-Assad last year. Now, the chemicals are a major test of the caretaker government led by the Hayat Tahrir al-Sham group. The group was designated as a terrorist organization by the United States but has abandoned its ties to al-Qaeda.
The stakes are high because of how deadly the weapons are, especially when used in densely populated areas. The nerve agent Shalin can be killed in minutes. Chlorine and mustard gas, notorious weapons in World War I, burned eyes and skin and filled lungs with liquid, appearing to be drowned on land.
Experts are concerned about the potential of militant groups to obtain poorly secure chemical weapons facilities.
Syria's foreign minister said in a surprise visit to the headquarters of the Global Chemical Weapons Regulatory Agency in March that the government would “destroy any remains of chemical weapons programs formulated under the Assad regime” and comply with international law.
Experts are cautiously optimistic about the sincerity of the government. According to people familiar with the trip, the current government allowed teams from watchdogs to enter the country and began recording work at these locations.
But Syria remains in a volatile position as violence broke out in coastal areas between government forces and groups that align with Mr. Assad in recent weeks. Despite the commitment, the new government has not yet appointed ambassadors to the supervisory body – a key first step that is seen as a sign of a nation's commitment. Syria's Ministry of Defense declined to answer written questions about weapons, saying that the issue was not stated was not under its jurisdiction.
In the early days of the Civil War, Mr. Assad's government announced 27 locations to the organization to ban chemical weapons or OPCW, which allowed inspectors to visit and shut them down. But Mr. Al-Assad continued to use chemical weapons until at least 2018, and studies have shown that his government has been importing essential precursor chemicals.
Current estimates of over 100 sites are from supervisory agencies and have recently been distributed among experts and international non-proliferation analysts. The group said its number is based on external researchers, nonprofits and intelligence shared by its member states.
Researchers, former organization staff and other experts say some sites may be hidden in caves or places that are hard to find in other places. This increases the possibility that some weapons are not fixed.
“We don't know where we don't know because the old regime is lying to the OPCW,” said Raed Al-Saleh, leader of the Syrian civil defense.
Nidal Shikhani, who leads the Syrian Center for Chemical Violations Documentation, has worked with the organization to ban chemical weapons, and for many years his team has identified dozens of new locations that can be stockpiles of chemical weapons or previous research sites based on interviews with scientists living in Syrian governments living in Europe.
Finding and controlling these sites is important for reasons other than security. The inspectors also hope to collect evidence to investigate the evidence of Mr. Al-Assad's repeated use of chemical weapons. International observers, independent researchers and Syrian humanitarian groups have documented dozens of attacks, including thousands, including victims. The most notorious is the 2013 attack on the Sarin Gas area of the Ghouta suburb of the capital Damascus.
Last year, Israel launched air strikes on several Syrian regime facilities, known to have chemical weapons in place. But it is not clear whether these strikes destroyed chemical weapons.
Mr Shikhani and others said they were worried that the strikes only caused environmental pollution and damaged the evidence. International groups hope chemical evidence will answer key questions about Assad's government research and help international prosecutions.
“The Israeli attacks following the collapse of Assad may not be trapped in some of the attacks, and it may have covered up the efforts to lie in the responsibility,” said Natasha Hall, a senior researcher in Washington.
Salin gas is prohibited under international law. These rules are more vague about other chemicals. For example, common household cleaning products can be used to create chlorine. This is almost impossible to regulate the sales of precursors.
According to former senior government chemists in Syria, Syria's chemical weapons program began in the 1970s, with many of the government scientists trained in Germany and other parts of Europe speaking out of anonymity for fear of retribution.
The scientist works in the Chemical Weapons Department of the Center for Military Science Research and Research. The Centre is under international sanctions and engages in conventional, chemical and nuclear weapons.
He and others said many scientists fled the country during the war, but others remained in Syria. The United States has imposed sanctions on more than 300 people and entities in Syria's chemical weapons program.
Despite the assurances of the new government, weapons inspectors are eased their optimism. They have heard such as guarantees in Syria before.
More than a decade ago, Syria first agreed to get rid of chemical weapons. However, when inspectors were doing their work, they were convinced that Mr. Al-Assad had no intention of revealing complete information about his stock. Former staff said they were forever bound by the government.
In an incident in 2014, inspectors and Syrian staff were investigating a potential location when a car in a convoy hit a roadside bomb. Two Syrians in the convoy accused the government of misleading them and ensuring their routes were safe. Other staff recalled constant fears that the government was eavesdropping on their conversations or surveillance them.
Mr. Al-Assad's government also covered up the attacks, which used Sarin and chlorine on their own people.
In the town of Zamalka near Damascus, the tombstone marks the names of many residents during the war and the date of their death. On the other side of the cemetery is a pile of dirt piled on the ground, with no mark of its meaning.
A local official said the town buried local men, women and children who were killed in a 2013 alleged chemical weapons attack. When Mr Assad's government recaptured the town in 2017, officials said the government removed the tombstone and covered the cemetery.
