The intelligence community in the United States is concerned that the Syrian government led by President Bashar Assad may deploy a large-scale chemical weapons attack as a last resort effort to protect regime strongholds from rebels in the embattled country, The Wall Street Journal on quoted US officials as saying on Sunday. According to the report, US intelligence agencies believe the possibility could materialize if the Damascus regime felt it had no options left to defend key territories and installations from Islamist insurgents and opposition forces in Syria's more than four-year civil war. Syria agreed to destroy its chemical weapons in 2013, but the Organization for the Prohibition of Chemical Weapons has since found that chlorine gas has been "systematically and repeatedly" used as a weapon. The group does not have a mandate to lay blame. In 2013, the United States threatened military intervention against Syria's government after sarin gas attacks killed hundreds of people in a Damascus suburb.Assad's government last year handed over 1,300 tons of chemical arms to a joint UN-OPCW mission for destruction. But Damascus has denied using sarin or any chemical weapons in battle during Syria's continuing civil war.The Wall Street Journal report cited officials as saying US experts and policy makers have been reviewing intelligence in aims of understanding the specific chemical arms Assad might now have stockpiled and what situations could spur their deployment. A senior US official told the Wall Street Journal that the matter was “being taken very seriously because [Assad]’s getting desperate.” The report also noted concern among the US intelligence community due to uncertainty over whether the Syrian government complied with international demands in 2013 to destroy all of the most deadly chemical weapons in its arsenal.The OPCW has been investigating allegations of dozens of recent chlorine gas attacks in Syrian villages, but it is being refused access to the sites by Assad's government, diplomatic sources have said. According to the Wall Street Journal, Syrian officials both in Damascus and New York made no comment on the report.