WASHINGTON – The US Senate was poised late Thursday to approve President Barack Obama’s plan for training and arming moderate Syrian rebels to battle Islamic State.A successful Senate vote on the measure, which passed the House of Representatives on Wednesday on a vote of 273-156, would send it to Obama to sign into law.The president plans to use the congressional authority to “degrade and destroy” Islamic State forces that have been taking control of large parts of Iraq and Syria – moves that US officials argue threaten America’s national security.The initiative has been attached to a bill that would keep the US government operating on October 1, the start of a new fiscal year. Under the measure, Obama’s authority to there are a number of questions here that still have to be clarified, still have to be looked at very closely” by international inspectors, the official said.In April 2013, IDF Military Intelligence was the first to accuse Assad’s regime of using chemical weapons against areas held by rebels in the civil war.Western powers soon echoed the charge and Washington threatened Damascus with air strikes.Assad agreed to give up the chemical arsenal, which Damascus had previously not acknowledged having.However, he denied his forces had used them and accused rebels of such attacks.International diplomats said this week that Syria had revealed a previously undeclared research and development facility and a laboratory to produce the ricin poison.Those disclosures appeared to support Western assertions in recent months that the Assad regime had not been fully transparent in detailing its chemical weapons program.The Israeli official said the 1,300 tons of mustard gas and precursors for sarin and VX surrendered by Syria largely matched Israeli assessments of its total stockpile of such materials. The shelf-life of any deployable munitions held back was limited given the chemicals’ deterioration, he added.Those assessments appear to contribute to overall Israeli relief at the Syrian chemical disarmament, even if Assad has reneged in part. The Israeli official voiced confidence that “our deterrence” – usually a coded reference to Israel’s superior military and assumed nuclear arsenal – would continue to keep Damascus in check.Using chemical weapons against Israeli targets, even on a small scale, “wouldn’t be a game-changer, it would be a game-ender” for Syria, the official said.He was less sanguine, however, when asked about the possibility that Islamic State insurgents in Syria and Iraq might get hold of Assad’s remaining chemical weapons.Israel had no indication that this had happened, he said, indicating Israeli intelligence knew where Assad’s remaining chemical arms were kept and that these sites were still safe – something he declined to confirm or deny directly.“I haven’t seen any information that they [Islamic State] have received them. I would not be surprised if they are interested, though, in receiving them,” he said.While using higher-yield munitions such as air-dropped bombs might be beyond the insurgents, they could easily carry out attacks with “a bunch of grenades with sarin” if this became available, the official added. He noted Israel’s concern at the entrenchment of Islamist rebels along the ceasefire line with Syria on the Golan Heights.According to regional sources, Israel has on several occasions bombed sites in Syria to thwart the suspected handover of conventional weapons from Assad to allied Lebanese Hezbollah guerrillas.Israeli officials have not formally confirmed carrying out the strikes but say they are poised to take similar action to prevent insurgents from getting chemical weapons.“When we have seen things that we are concerned about, whatever has been done has been done, and that’s it. We have been very careful not to be sucked in. So that policy will continue,” the official said.Reuters contributed to this report.