CIA Director: ISIS Has Used and Can Continue to Make Chemical Weapons

The Islamic State militant group (ISIS) has the capability to continue making small quantities of chlorine and mustard gas, according to CIA Director John Brennan.

The U.S.'s intelligence chief is due to appear in an interview on CBS News's 60 Minutes program on Sunday but the channel released snippets from the interview late Thursday. In the interview, he said that ISIS has already used chemical weapons on the battlefield a number of times.

"We have a number of instances where ISIL has used chemical munitions on the battlefield," he said, using an alternate acronym for the militant group.

Brennan said that despite the setbacks the group has faced because of the U.S.-led coalition campaign, it has retained the ability to develop deadly munitions.

"There are reports that ISIS has access to chemical precursors and munitions that they can use," he said.

He also warned that the radical Islamist group may attempt to sell on the weapons that they develop into Western countries.

"I think there's always the potential for that. This is why it's so important to cut off the various transportation routes and smuggling routes that they have used," he said.

Brennan was challenged about the U.S. role in Syria and Iraq and whether the intelligence agency was attempting to prevent ISIS weapon-making operations, but he would not elaborate further other than saying that the U.S. is trying to destroy the radical Islamist group however possible.

"U.S. intelligence is actively involved in being a part of the efforts to destroy ISIL and to get as much insight into what they have on the ground inside of Syria and Iraq," he continued.

U.S. Director of National Intelligence James Clapper said this week that ISIS's development of chemical weapons was the first instance of an extremist group doing so since Japan's Aum Supreme Truth cult used sarin gas in a rush-hour attack on the Tokyo subway in 1995.