More than 11 days have passed since a suspected chemical weapons attack in Syria left dozens of people dead, yet it is still unclear when independent investigators will gain access to the site to work out what happened.
Confusion has swirled over when a fact-finding team of experts from the Organisation for the Prohibition of Chemical Weapons (OPCW) will be able to enter the city of Douma, prompting concerns that repeated delays could stymie its mission.
The team was widely expected to visit Douma on Wednesday, but a United Nations security team carrying out reconnaissance in the city came under fire Tuesday, further delaying experts from going in, a UN source told CNN. No one was injured, and the team returned to Damascus, the source said.
The OPCW team has been in Syria since Saturday but has failed to reach Douma. The UK envoy to the OPCW, Peter Wilson, on Monday accused Syria and Russia of blocking the team's access to the site, which Russia denied. Syria said the experts could go to Douma after getting clearance from the UN security team.
The OPCW experts are tasked with finding out whether chemical weapons were used in the April 7 strike. US officials have said they believe chlorine and sarin gas were dropped there.
The US, UK and France have blamed Syrian President Bashar al-Assad's regime for the attack and together carried out airstrikes over the weekend in response, with the support of other Western nations.
The OPCW would not reveal to CNN its team's whereabouts, saying it was unable to share operational details to "to preserve the integrity of the investigatory process and its results," as well as for security reasons.
Syrian state TV and the White Helmets volunteer rescue group said separately on Tuesday that the OPCW team had arrived in the area, only to be contradicted by a US State Department spokeswoman.
Both Syria and its powerful ally, Russia, deny a chemical attack took place, and Russia has claimed it was "faked" or "staged," with the help of British intelligence agencies. Britain denies the allegation.
'Every day matters'
Jerry Smith, a former chemical weapons inspector in Syria and founder of the RameHead Consulting International security firm, warned that a substance like chlorine could "disappear in a couple of hours."
"Every day matters," he told CNN recently. "The greater the time between when it's released and when it's detected, the chances of it being found reduces."
Nerve agents, however, can often be detected for years.
The US envoy to the OPCW, Kenneth Ward, said on Monday he was concerned Russia may have "tampered with" the site of the Douma attack.
"This raises serious questions about the ability of the (team) to do its job," Ward said.
Russia has openly announced that its representatives have been to the site, and a CBS journalist has also accessed the site, reporting from the location in recent days.
Russian Foreign Minister Sergey Lavrov told the BBC's "HARDtalk" that he guaranteed there had been no Russian tampering, adding his country had sent experts to the site and found "no trace" of chemical weapons.
Russian state-run media outlet TASS said a team from its conflict monitoring center in Syria had examined Douma on April 9, two days after the alleged attack, and found no sign of chemical use.
Russia and US lock horns
Already-strained relations between Russia and the Western allies that launched the coordinated strikes on Syria have deteriorated in recent days. Information on the attack site is murky, and different sides are giving conflicting details and accusing one another of cooking up conspiracy theories.
The Russian military said Tuesday in state media it had discovered a chemical laboratory and warehouse in Douma allegedly run by "militants." CNN could not corroborate that allegation.
US and Russian representatives once again went head to head Tuesday over Syria at a UN Security Council meeting.
Russian Ambassador to the UN Vassily Nebenzia called the behavior of the US, the UK and France "hypocritical."
"Not even a day passed after the missile strikes when their organizers started putting forward strange and political initiatives," Nebenzia said.
Nebenzia went on to call Washington and its allies "self-appointed executioners" and accused them of pressuring Russia to change its position after the latest round of airstrikes and a promised new round of sanctions.
Russian media reported that the Security Council meeting, convened at the request of Russia, focused on the humanitarian situation in ISIS' former stronghold of Raqqa and displaced persons in the Al-Rukban refugee camp on the border with Jordan
Kelley Currie, a US representative to the UN, accused Russia of distracting from the atrocities committed by the Assad regime.
"In order to do that, Russia has asked this council to focus its attention on the one part of Syria where the Assad regime isn't pummeling civilians to death with barrel bombs or banned chemical weapons," Currie said.
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