UNITED NATIONS —
Paulo Sergio Pinheiro said the Geneva-based U.N. panel he heads has not pinpointed the chemical used in the attacks and is awaiting evidence from a separate team of U.N. chemical weapons inspectors expected to be made public later Monday.
That report is expected to add momentum to a deal to eradicate Syria's chemical weapons program.
Pinheiro also said the panel believes Assad's government has been responsible for war crimes and crimes against humanity, while rebel groups have perpetrated war crimes but not crimes against humanity "because there is not a clear chain of command."
U.S. Secretary of State John Kerry ended a weeklong diplomacy tour in Paris on Monday. Just a week ago, he was there lobbying for global support for military strikes against Assad, but after a breakthrough with Russia, Kerry's latest visit was intended to secure support from allies for the deal to secure and then eradicate Syria's chemical weapons arsenal.
Kerry and his French and British counterparts laid out a two-pronged approach in Syria, calling for enforceable U.N. benchmarks for eradicating the chemical weapons program and an international conference bolstering the moderate opposition.
France and the U.S. insisted that a military response to the Aug. 21 poison gas attack that killed hundreds remained on the table, and were pressing for a U.N. resolution reflecting that in coming days.
"If Assad fails to comply ... we are all agreed, and that includes Russia, that there will be consequences," Secretary of State John Kerry said.
But Russia's foreign minister said ongoing attempts to threaten the use of force against Syria would provoke the opposition and disrupt a chance for negotiations.
Russian Foreign Minister Sergey Lavrov, in a news conference with his Egyptian counterpart Nabil Fahmy, responded to comments by French President Francois Hollande that the "military option" against Syria was not off the table.