By Alexei Anishchuk
VALDAI, Russia (Reuters) - Russian President Vladimir Putin said on Thursday he could not be 100 percent certain a plan for the destruction of Syrian chemical arms would be carried out successfully but he saw reason to hope it would.
Putin, whose country has been the Syrian government's main ally in the more than two-year-old civil war, praised U.S. President Barack Obama for not carrying out threats of a military strike over a poison gas attack in rebel-held areas.
He said such a strike would violate international law and reiterated suspicions that Assad's opponents had staged the attack, which killed hundreds of people on August 21, to encourage military action by the United States.
"Will we be able to accomplish it all (the destruction of Syria's chemical arms)? I cannot be 100 percent sure about it," Putin told a gathering of journalists and Russia experts.
"But everything we have seen so far in recent days gives us confidence that this will happen ... I hope so."
The former KGB spy said the "primitive" make of the warhead used for the attack provided strong grounds to believe it was staged by Assad's foes and that other alleged chemical weapons attacks in Syria also needed to be investigated. Washington says it believes the attack was carried out by Assad's forces.
"We always talk about the responsibility of the Assad government, if he was the one who used it (a chemical weapon). What if the opposition used it?," Putin said. "We have every reason to believe it was a cunning provocation."
Russia and the United States brokered a deal on Saturday to put Assad's chemical arms stockpiles under international control to avoid possible U.S. military strikes that Washington said would be intended to punish him over the gas attack.
Such a strike, Putin warned, "would be a strike on world order, not on Syria."
He complained that the threat of military action held out by Washington and other Western allies was poorly thought through and could have the unintended consequence of helping al Qaeda militants come to power.
"His (Obama's) decision was based on a real analysis of the situation, and I am very happy that our positions matched on this issue," he said.
"The United States has admitted that al Qaeda is fighting there. When I speak to my colleagues, I ask them: 'Okay, you in fact want to take their side, help them come to power. Then what?'," Putin said.
Under the U.S.-Russian deal, Assad must account for his chemical weapon stockpiles within a week and see them destroyed by mid-next year.
(Reporting by Alexei Anishchuk; Writing by Alissa de Carbonnel, Editing by Timothy Heritage and Ralph Boulton)