Syrian president Bashar Assad still has up to three tons of chemical weapons, Israeli defence officials said.
They delivered the assessment weeks after a chemical attack in Syria killed at least 90 people.
Israel, along with much of the international community, believes that Assad's forces carried out the attack.
Israeli military intelligence estimates that Assad has "between one and three tons" of chemical weapons, a senior military official said.
The assessment was confirmed by two other defence officials.
Assad has denied the allegations that he was behind the April 4 attack.
Syria agreed to give up its chemical weapons arsenal in 2013.