Syria on Monday handed over to Western governments the last of the chemical weapons stockpile that it has acknowledged having, although doubts remain about whether all toxic weapons have truly been removed from the increasingly unstable region.

The milestone comes amid tense days across the Middle East, as Israel carried out strikes Monday on Syria in response to a Syrian attack in the Golan Heights a day earlier, and a Syrian cabinet member warned that Sunni insurgents in neighboring Iraq have been transferring weapons and equipment to rebel allies in Syria.

During a visit to Baghdad, U.S. Secretary of State John Kerry hailed the Syrian handover of the stockpile as a significant step toward diminishing the threat of chemical warfare in the region, but warned that the use of chlorine gas remains a serious issue amid the three-year war in Syria that has claimed an estimated 160,000 lives. […]