Russian investigators, who had direct access to the site of the March 19 attack on the government-controlled Aleppo suburb of Khan al-Assal, found evidence of crudely made sarin, a lethal nerve agent, that was embedded in an unguided Basha'ir-3 rocket with a crude explosive charge -- not the sort of munitions stockpiled by the Syrian military, Russian Ambassador to the United Nations Vitaly Churkin told reporters.
"Therefore, there is every reason to believe that it was armed opposition fighters who used the chemical weapons in Khan al-Assal," Churkin said in the news conference, which can be seen at tinyurl.com/UPI-Churkin-News-Conference.
Production of Basha'ir-3 rockets was begun in February by the Basha'ir al-Nasser Brigade, affiliated with the opposition Free Syrian Army, Churkin said.
"This was like a cottage-industry product, manufactured at a simple facility," he said.
Churkin did not release the Russian analysis, which he said was 80 pages long and supported with chemical formulas and graphs.
He said he delivered the analysis to U.N. Secretary-General Ban Ki-moon Tuesday and planned to forward copies to his U.S., French and British counterparts.
"I hope they find it persuasive," he said.
Acting U.S. Ambassador to the United Nations Rosemary DiCarlo told reporters later the United States hadn't "received the report yet but we will certainly study it carefully when we do receive it."
She said the Obama administration has "long called for governments to provide information to the United Nations on possible use of chemical weapons in Syria."
In June, the Obama administration concluded forces loyal to Syrian President Bashar Assad's regime used chemical weapons in the March 19 Khan al-Assal attack that killed at least 26 people. It also said the regime used chemical weapons three other times, including in the Damascus suburbs, killing 100 to 150 people.
The U.S. finding, dismissed by Moscow, was based in part on indirectly acquired soil samples and interviews with survivors. Churkin stressed Russia's samples were based on direct access to the soil samples.
The White House conclusion the regime used chemical weapons "on a small scale against the opposition multiple times in the last year," as White House spokesman Jay Carney described it June 13, helped form the basis for the administration's decision to supply small arms and ammunition to the insurgents.
The White House said Tuesday it had no reason to alter its view.
"We have yet to see any evidence that backs up the assertion that anybody besides the Syrian government has had the ability to use chemical weapons or has used chemical weapons," Carney told reporters.
He noted Russia is the Assad regime's most powerful ally and said Moscow's findings called attention to Assad's refusal to let U.N. investigators into the country to probe the chemical weapons allegations.
After the Khan al-Assal attack, the Assad regime asked for a U.N. investigation.
But it then refused to let inspectors in after Ban asked for permission to investigate British and French claims Damascus used chemical weapons at Khan al-Assal and elsewhere in Syria.
Churkin said Russia's investigation was carried out at the request of the Assad regime after the U.N. investigation "unfortunately ... did not materialize."
Ban spokesman Martin Nesirky said the Russian report would be studied by the U.N. Office for Disarmament Affairs, which would send its conclusion to Ban.