Al-Qaeda’s main affiliate in Iraq avoided extinction at the hands of U.S. and Iraqi forces a decade ago by backing away from military engagements and moving the remnants of its network underground until its reemergence as the Islamic State.

That successor organization, now confronting its own eventual fall, is devising a modified survival strategy that may involve surrendering control of its “caliphate” in Iraq and Syria but seeks to preserve a virtual version of it online.

That plan is described in a new report on the Islamic State’s evolving media strategy as its physical territory shrinks. The study, published by King’s College London, warns that it is premature to imagine a “post-Islamic State world at this time.”

“The organization has used propaganda to cultivate digital strategic depth,” the study concludes, using a term that traditionally applies to a mountainous region or other terrain that a nation can retreat to and defend. “Due to this effort, the caliphate idea will exist long beyond its proto-state.”

As part of this strategy, the ­Islamic State’s media wing has already begun to repurpose videos, images and messages from its massive collection for new propaganda releases that depict the ­Islamist state it sought to establish as an idyllic realm destined to be restored.

“If compelled to, the group’s true believers will simply retreat into the virtual world, where they will use the vast archive of propaganda assembled by the group over these past few years to keep themselves buoyant with nostalgia,” the report said.

The plan reveals a level of desperation for a terrorist organization that has seen its territory shrink rapidly over the past year. But it also serves as the latest example of the group’s innovative approach to using the Internet and social media — first to draw recruits to the fight in Iraq and Syria and now to preserve the loyalties of its dispersed followers.

[They’re young and lonely. The Islamic State thinks they’ll make perfect terrorists.]

The King’s Collegereport draws many of its conclusions from an Islamic State propaganda guidebook that surfaced online last year. Called “Media Operative, You Are a Mujahid, Too,” the booklet equates propaganda teams with armed operatives in their importance to the terrorist group and provides guidance on how to ­develop messages that exploit mainstream media coverage and advance the organization’s ideology.

“Media weapons [can] actually be more potent than atomic bombs,” one passage proclaims, according to the King’s College report.

A video released by the Islamic State this month appears to be drawn from the organization’s evolving playbook. Titled “Building Blocks,” the video mixes typical footage of fighters with scenes of workers paving streets, firetrucks leaving stations and shoppers perusing stocked shelves.

Charlie Winter, a senior research fellow at the International Center for the Study of Radicalization at King’s College and the author of the new report, described the video as a “good example of the kind of pre-emptive nostalgia” that the Islamic State is seeking to elicit, one that “seems geared toward offering evidence of the good old days, of the caliphate that once was, even before it’s lost.”

Beyond losing territory under military pressure from the United States, Turkey, Russia, Syria and Iraq, the Islamic State has seen the flow of foreign fighters into its ranks plummet — from as many as 2,000 a month two years ago to as few as 50, according to recent assessments.

The group began altering its propaganda themes last year to prepare followers for the collapse of the caliphate, depicting its mounting battlefield losses as ­noble and inevitable struggles, in contrast to the triumphant messages that had previously dominated its output.

The emerging media strategy faces significant challenges. The Islamic State’s audience online has shrunk, though it is unclear by how much, in part because social media companies, including Facebook and Twitter, have more aggressively removed Islamic State supporters and their content.

Still, experts said the plan to maintain its online following could enable the Islamic State to reemerge much the way its predecessor did when Syria fell into civil war.

The group is “trying to hold onto a much more ambitious version of itself than it did a decade ago,” said Alberto Fernandez, a former senior U.S. State Department official and expert on Islamic State media. The organization is moving into “kind of a holding pattern,” he said. “The question is, holding pattern for what and for where and for when?”

The Islamic State has sought to compensate for territorial setbacks by seeking to carry out terrorist plots in Europe and the United States as a way to demonstrate its relevance as a global force.

In Iraq and Syria, the network has already shifted toward more traditional insurgency tactics. It claimed credit for the recent bombing of a restaurant in Mosul and is likely to continue to mount such operations to destabilize territory the group has been forced to surrender — and also to provide footage for new propaganda releases.

“Broadly speaking, we’ll see the Islamic State reverting to type, looking more like a run of the mill terror group rather than a proto-state,” Winter said. “They’ll put a huge amount of effort into producing content, but also recirculating content. Their claims about just how utopian it was will become even more exaggerated.”