The Syrian government may be developing new types of chemical weapons, and U.S. President Donald Trump is prepared to again order military action against Syrian leader Bashar al-Assad's forces if necessary to deter chemical attacks, senior U.S. officials said on Thursday. Assad's government is believed to have kept part of its chemical weapons stockpile despite a U.S.-Russian deal under which Damascus was supposed to have handed over all those weapons for destruction in 2014, the officials said. Assad's forces have continued occasional use of chemical weapons in smaller amounts since a deadly attack last April that drew a U.S. missile strike on a Syrian air base, the officials told reporters in a briefing. Characteristics of some of those recent attacks suggest that Syria may be developing new weapons and methods for delivering poison chemicals, possibly to make it harder to trace their origin, the officials said, speaking on condition of anonymity. But they declined to provide specifics. A deadly sarin attack on a rebel-held area in April prompted Trump to order a missile strike last year on the Shayrat air base, from which the Syrian operation is said to have been launched. "We reserve the right to use military force to prevent or deter the use of chemical weapons," one official said, while declining to specify how serious a chemical attack would have to be to draw a fresh U.S. military response. If the international community does not act quickly to step up pressure on Assad, Syria's chemical weapons could spread beyond Syria and possibly even "to U.S. shores," a second official said. "It will spread if we don't do something," the official warned. The officials reiterated U.S. Secretary of State Rex Tillerson's recent accusation that Russia, Assad's ally in Syria's multi-sided civil war, bears some responsibility for failing to enforce the chemical weapons ban. Russia has denied any complicity, and the Syrian government has said it has not carried out any of the attacks. Most recently, Western officials have cast suspicion on the Syrian government for a chlorine gas attack on a rebel-held enclave east of Damascus last week that sickened at least 13 people. The U.S. officials also said Islamic State (IS) militants have used chemical weapons such as sulfur mustard and chlorine and have employed improvised explosive devices to deliver the chemicals.
