Paris attacks: ISIS has secret branch of scientists developing CHEMICAL

Biological weapons can include agents like anthrax, cholera, and the plague.

US intelligence officials told NBC News that ISIS was the non-state actor.

Today, French prime minster Manuel Valls warned ISIS extremists could use chemical weapons in their next attack.

The official said ISIS has a cell dedicated to building these weapons and has already packed the powder form of mustard gas in traditional explosives.

In August, it was confirmed that Kurds fighting ISIS in northern Iraq were exposed to mustard gas.

"It's only acceptable when the regime or any other group uses chemical warfare against us?" he wrote.

He added that it is likely they will turn to chemical weapons, which he described as "the ultimate terror weapon", in order to do that.

"Fight them the way they fight you". Syria had supposedly surrendered the chemical 18 months ago, and the confirmation that mustard gas was used in August raises several questions.

The USA ambassador to Canada is using yet another name - "Daesh" - for the multi-monikered terrorist group known variously as the Islamic State of Iraq and the Levant (ISIL), the Islamic State of Iraq and Syria (ISIS) and the Islamic State.

But al-Zamili, citing intelligence reports he has access to, told the AP that the group has managed to attract chemical experts from overseas as well as Iraqi experts, including ones who once worked for Saddam Hussein's now-dissolved Military Industrialization Authority. NBC News has not been able to confirm that assessment.

"We have seen them use improvised chemical weapons like chlorine in Syria and that is a threat that could be used to create terror on the streets of Europe and elsewhere", he said.

"Whether ISIL is manufacturing chemical weapons themselves or acquired from former or current stocks maintained by Bashar Assad, this is a potential nightmare scenario for our partners in the Middle East, and for us", Sen.

"They don't deploy it on wide scales", Martin said.

Martin said that's still unclear.

"Mosul [seized by ISIS in June] has a university and that theoretically has the lab facilities to deal with this". There are also concerns about militants trying to obtain radioactive materials.

But retired Lt. Gen. Richard Zahner, who was the top American military intelligence officer in Iraq in 2005 and 2006, told the AP that US intelligence agencies have consistently underestimated the terrorist group in the past, and noted that ISIS has greater financial resources than al Qaeda, which tried and failed to develop chemical weapons for two decades.