Several sources, within both law enforcement and outside think tanks, have recently warned the Western world not to underestimate the threat of the Islamic State.

There are fears battlefield reversals in Syria could prompt even more Paris-style attacks on soft targets in the West, and that jihadis driven from the field will return home to threaten their countries of origin.

The FBI’s recently-promoted Assistant Director for Intelligence, Joshua Skule, told WTOP.com that Washington, D.C. faces a “constant and persistent threat” from ISIS, which has moved beyond mere “wishful thinking” and begun actively recruiting operatives in the D.C. area.

WTOP cites the example of Ali Shukri Amin, who pleaded guilty last summer to providing material support to ISIS, including advice on how they could use the digital currency Bitcoin to hide their financial transactions. Amin also helped Reza Niknejad of Prince William County, Virginia to travel to Syria for military training with the Islamic State.

Amin is only 17 years old, while Niknejad is 18.

“They are prolific on the web. Their propaganda message on social media has been consistent and it has resonated, as our director has said, with lost souls looking for a place to go,” said Skule, referring to FBI Director James Comey.

Skule added that the flow of foreign fighters into ISIS-controlled areas is something “never seen to the volume that the world has seen today.”

Business Insider highlighted last week a joint report by the Institute for the Study of War and the American Enterprise Institute, prepared with the help of experts who planned the 2007 troop surge in Iraq. The report described a veritable assassin factory in Syria, cranking out operatives with enough weapons, explosives, and tactical training to wreak incredible carnage on civilian targets in Western cities.

It is not just ISIS nourishing a “lone wolf jihadi” army, either. The joint report suggested Western security services are underestimating Jabhat al-Nusra, also known as the Nusra Front.

“This Al Qaeda affiliate has established an expansive network of partnerships with local opposition groups that have grown either dependent on or fiercely loyal to the organization,” said the report. “Its defeat and destruction must be one of the highest priorities of any strategy to defend the United States and Europe from Al Qaeda attacks.”

The report further warned that the current strategy of pursuing a “diplomatic solution” in Syria was likely to make al-Nusra even stronger, as they rallied support from groups that simply refuse to accept a negotiated settlement that leaves Bashar Assad or his designated successors in power.

Also last week, the Washington Times reported on a chilling propaganda video from ISIS that showed the group “has the machinery in place to attract recruits from the West, mold them into assassins and then dispatch them back to Europe to commit mass murder, such as the carnage in Paris on Nov. 13.”

The video boasts that ISIS has created a production line for manufacturing jihadis, including training camps that appear to be located somewhere in Europe. The Paris attackers are saluted, while British Prime Minister David Cameron and French President Francois Hollande are specifically targeted for assassination. European law enforcement agencies report a high level of chatter between ISIS supporters about launching another massacre along the lines of Paris.

Analysts distilled the message of the video into two core points: the Western world will never know peace as long as it fights the Islamic State, and Muslims living in the West should carry out jihad attacks at every opportunity.

This is consistent with the threat Skule described to American cities, especially those with symbolic value comparable to Paris, such as New York and Washington.

“ISIL is the most prolific threat we have faced,” he declared. “Their call to jihad and their message to kill at every turn is something we have never undertaken or faced, even with core al-Qaida. It would give a terrorist organization no greater benefit than to attack the seat of power in the U.S.”

All of the analysts cited above agree that conditions in Syria and Iraq increase the risk of jihad attacks in the U.S. and Europe. Terror attacks in the West provide a means of restoring credibility lost due to battlefield defeats in the Middle East. Disappointed jihadis retiring from the ISIS front lines will return “home” with their savage ideology intact. Military-age recruits who have second thoughts about heading for Syria may decide to conduct jihad operations back home instead.

If the Islamic State looks to be in severe decline, rivals in the al-Qaeda network will want to assert dominance and make a name for themselves with headline-grabbing terrorism. The joint ISW-AEI report on Jabhat al-Nusra warned that al-Qaeda might be much further along in preparing for operations in the U.S. and Europe than most people think, taking advantage of the global focus on ISIS to distract attention from their activities.

“US policymakers are underestimating Jabhat al-Nusra because Jabhat al-Nusra wishes to be underestimated,” warned report author Kimberly Kagan of the Institute for the Study of War. “We are so focused on ISIS that we are not looking at the second threat.”