By all accounts, the Islamic State has gone 'underground' and its fighters on the run, especially following the death of terror chief Abu Bakr al-Baghdadi. The concern now amid renewed chaos in northern Syria due to Erdogan's 'Operation Peace Spring' is the potential for mass ISIS jail breaks — in some instances already occurring — as well as terrorists fleeing back across Turkey's notoriously porous southern border. There's also the question of ISIS taking refuge in Idlib, which its leader apparently did, also caught a mere three miles from the Turkish border.

And now, ISIS is signalling a new threat to Europe and the United States, as FOX reports this week:

At least four propaganda posters have appeared in recent months from the pro-ISIS media outlet Quraysh Media that have encouraged followers to "ignite fires" of their own, literally setting wildfires in the U.S. and Europe as a means of "waging jihad," according to the Middle East Media Research Institute [MEMRI].

Pro-ISIS media outlet released this propaganda poster, via the Middle East Media Research Institute.

MEMRI translated the poster as follows: "Oh monotheists [followers of ISIS], ignite fires in the forests and fields, and we are addressing especially those who live in Europe and America, for they are painful to them."

The threatening posters have actually appeared over the past months, and began to gain more attention given the massively destructive wildfires which have raged over the past month in places like California and Lebanon. In the case of Lebanon, it should be noted, fires which came near the outskirts Beirut were specifically identified to be the result of arson.

Pro-ISIS media outlet released this propaganda poster, via the Middle East Media Research Institute.

The subsequent series of "jihad posters" appeared in the early summer, and the most recent as late as Monday of this week. Some depict American firefighters struggling against out of control blazes.

The latest poster (fourth in the series) threateningly names specific countries which should be targeted by ISIS followers in arson attacks.

"Ignite fires in the forests of America, France, Britain and Germany, for they are painful to them," the text reads, according to MEMRI.

It's as yet unclear if any ISIS recruits in the West have actually attempted to act on the propaganda instructions; however, it's a significant security threat which European and US authorities will no doubt be on high alert for in the coming months.

There's also the danger that ISIS-sympathizers living in the West could conduct attacks "inspired" of the crude ISIS propaganda threat.