TEL AVIV – In an admission with international security implications, America’s top intelligence official on Tuesday confirmed the Islamic State has successfully produced and deployed chemical agents in Iraq and Syria.

Director of National Intelligence James Clapper told the Senate Armed Services Committee that IS had previously utilized mustard gas, evidencing the continued advancement of the terrorist organization’s sophistication on the battlefield.

“[The Syrian government] has used chemicals against the opposition on multiple occasions since Syria joined the Chemical Weapons Convention. ISIL has also used toxic chemicals in Iraq and Syria, including the blister agent Sulfur mustard,” stated Clapper.

Fox News quoted Clapper stating IS’ use of the mustard agent marked the first time an extremist group has produced and used a “chemical warfare agent in an attack since Aum Shinrikyo used sarin in Japan in 1995 (in the Tokyo subway terror attack).”

Clapper’s statements to the committee were based on the U.S. Intelligence Community’s Worldwide Threat Assessment for 2016 released on Tuesday.

That 29-page report, reviewed by Breitbart Jerusalem, states, “Use of chemical weapons in Syria by both state and nonstate actors demonstrates that the threat of WMD is real.”

Continued the report:

We assess that nonstate actors in the region are also using chemicals as a means of warfare. The OPCW (Organization for the Prohibition of Chemical Weapons) investigation into an alleged ISIL attack in Syria in August led it to conclude that at least two people were exposed to sulfur mustard. We continue to track numerous allegations of ISIL’s use of chemicals in attacks in Iraq and Syria, suggesting that attacks might be widespread.

The use of sulfur mustard in Syria coupled with other recent reports and warnings highlights the possible threat of Islamic State radicals carrying out chemical attacks on Western targets.

The threat was red-flagged in November – one week after the Nov. 13 jihadist massacre in Paris – in the form of an unusual warning from French Prime Minister Manuel Valls, who said his country is at risk of chemical and biological terrorist attacks.

The intelligence community has widely believed IS possesses the ability to manufacture chemical weapons, and the jihadist group has already been accused of using them against civilians in Iraq and Syria.

In September, a U.S. official told the BBC that the American government is increasingly certain that IS extremists are making and using chemical weapons, including mustard gas. The official said IS has a cell dedicated to building these weapons and has already packed the powder form of mustard gas in traditional explosives.

That information was echoed by U.S. and Iraqi officials in comments made to the Associated Press in November.  The officials confirmed IS is aggressively pursuing the development of chemical weapons.

Perhaps more alarming is the threat of Western IS fighters trained in the use of chemical weapons returning to Europe and the U.S. from Iraq and Syria.

In March, an Egyptian intelligence official told this reporter the Egyptian government provided the US with information that indicated IS is attempting to purchase chemical materials such as chlorine gas that can be utilized in terrorist attacks.

Also in March, the Kurdistan Regional Security Council in Iraq claimed IS had deployed weaponized chlorine gas in recent attacks. Battlefield use of the deadly substance is banned by the international Chemical Weapons Convention.

The Kurdish claim was not independently verified. However, the BBC reported that the Iraqi government presented the news agency with “evidence” that IS fighters were using chlorine gas in roadside bomb attacks, with videos showing bomb disposal teams carrying out controlled explosions that sent orange smoke into the air, a sign that the gas was present.

In addition, a chemical weapons expert warned that IS militants returning to the West could deploy chemical weapons inside the U.S. or Britain, perhaps against transportation infrastructure or at a sports stadium.

Hamish de Bretton-Gordon, a former commanding officer at the Joint Chemical Biological Radiological Nuclear Regiment, warned, “It is very evident that ISIS are putting much time and effort into training its jihadis in the use of chlorine as a terror weapon and in particular in IEDs (improvised explosive devices).”

Writing at 2paragraphs.com, Bretton-Gordon continued, “Virtually every foreign jihadi who returns to the U.S. or U.K. will have been exposed to training of this sort and will have a reasonable idea on how to use chlorine and other toxic chemicals as a terror weapon.”

He noted that, in the U.K. at least, up to 90 tons of chlorine can be purchased without a license.

Bretton-Gordon, who advised British security forces in Baghdad last year, told the London Daily Mirror that a chlorine gas attack in the U.K. was “highly likely.”

“This could happen on a train or tube or even at a big football match.”

Aaron Klein is Breitbart’s Jerusalem bureau chief and senior investigative reporter. He is a New York Times bestselling author and hosts the popular weekend talk radio program, “Aaron Klein Investigative Radio.” Follow him on Twitter @AaronKleinShow. Follow him on Facebook.