Russian President Vladimir Putin said on Thursday in Moscow that he could not be 100-percent certain a US-Russian plan for the destruction of Syrian chemical arms would be carried out successfully.

"But everything we have seen so far in recent days gives us confidence that this will happen," he said, adding, "I hope so."

US Secretary of State John Kerry told reporters in Washington that it was essential the deal reached last Saturday be enforced and that the UN Security Council be willing to act on it next week, when the UN General Assembly holds its annual meeting in New York.