Doctors say that Syrian President Bashar Assad’s forces probably are using “Agent 15,” which causes paralysis, but the even worse news is that he has more deadly chemical weapons.

The Syrian American Medical Society (SAMS) interviewed witnesses and victims of the recent gas bomb attack, Business Insider reported.

The doctors said that Agent 15 was most likely used, but they could not confirm their conclusion without laboratory tests.

The effects of the gas bombs were felt immediately, with victims complaining they saw white gas, which they also smelled. They suffered shortness of breath, loss of vision, inability to speak, dizziness, nausea and paralysis.

Complicating their condition is the problem of using atropine needles, a common antidote to nerve gas, which actually is a toxic combination that can lead to death, according to Business Insider.

The use of chemical weapons, banned by international law, is seen as a sign of desperation by Assad. Continued attacks with chemical weapons will force President Barack Obama to decide whether to carry out his threat of military intervention in the event that chemical weapons were used.

Assad’s stockpile of chemical weapons includes lethal Mustard gas, as well as Sarin and VX, all of which can cause death following an even mild exposure to the agents.

Evidence of Assad’s concern about foreign intervention is a report in Iranian media, controlled by the government, that Assad’s’ regime has stated it is “genuinely worried” that “Syria’s enemies” could provide chemical weapons to rebels “and then claim they had been used by the Syrian government.”

Iran is Syria’s last remaining ally, with Russia beginning to distance itself from Assad. Moscow said last week there are other countries that could give the Syrian leader safe haven, but that it would not do so.