PARIS — By sending warplanes to bomb Islamic State in Syria and Iraq, Western powers wanted to punish the terrorist group on its turf — and avoid a blowback on the home front.

That logic looks increasingly shaky.

In the wake of last November’s attacks in Paris, U.S. and EU intelligence officials are reassessing their view of the self-described Islamic State’s strategic objectives to take into account its battlefield setbacks and need for propaganda victories.

They now believe the group, also known as either ISIS or ISIL, is determined to prove its continued strength by staging further attacks in the European Union. Their working scenario resembles the Paris tragedy, but on a vaster scale — with commando teams attacking soft targets in several countries at once, according to terrorism experts in France, Britain and the United States who were briefed on non-public discussions.

“The next attack is likely to be bigger,” said former French intelligence official Claude Moniquet, who heads the European Strategic Intelligence and Security Center. “The type of attack that intelligence and security agencies are preparing for now is a coordinated attack in multiple sites, in several major [EU] cities — two to four.”

ISIL likely has an “external actions” command to organize commando-style operations, and small training camps in the EU and Balkan countries, according to Europol.

French Prime Minister Manuel Valls underscored those fears when he said last week that the terrorist threat in his country had “never been higher.” But France is just one of the EU countries in ISIL's crosshairs.

In propaganda videos published over the past few weeks, ISIL fighters warned of imminent, major attacks against France, Britain, Italy and Spain — the last one as punishment for having expelled Muslim rulers from Andalusia 500 years ago.

It's not just the Islamic State that is worrying Western authorities. Several experts warned about the threat of "me-too" attacks by Al Qaeda, which remains a force to be reckoned with despite having been superseded on the ground by ISIL in Syria and Iraq.

“When the Islamic State stages an attack in Europe, it serves the purpose of claiming leadership of global jihad for the group,” said Florian Otto, head of Europe and Central Asia at the Verisk Maplecroft risk consultancy in London. “This means Al Qaeda is under pressure to show it still exists."

Shift in strategy

To explain why ISIL, which previously focused only on expanding its so-called "Caliphate" in the Levant, would seek to strike faraway enemies, experts pointed to the group’s defining need for constant propaganda "victories."

Two years ago, battlefield gains in Syria and Iraq fed a narrative of constant expansion. Exploits were filmed, turned into propaganda videos and broadcast, helping to attract thousands of volunteer jihadis from around the world.

Since the launch of a U.S.-led bombing campaign against ISIL last August, the group has lost more than 14 percent of its holdings in Iraq and Syria, according to the New York Times, as of the end of 2015. Under constant scrutiny from coalition warplanes and drones, it can no longer openly parade intimidating columns of pickup trucks on the region’s highways.

Despite other gains, notably in Syria and Libya, and a frequent output of execution videos, ISIL has less fodder for boasting. It faces more contradiction to claims of an "Islamic paradise" from reports of difficult life conditions under its rule.

Yet the Islamic State still relies on propaganda to maintain its dominance in the ranks of global jihad and draw new recruits to expand the Caliphate, which remains its number-one strategic goal. In the absence of battlefield triumphs, experts said ISIL can fill a void by staging further, spectacular attacks in the West that garner instant, global coverage.

Nearly 2,000 fighters have returned to Europe after stints in Iraq and Syria, out of some 5,000 who left in the first place.

“The fact that ISIS has come under more pressure [from bombing] over the course of the last year — this has probably created an incentive to demonstrate its continued strength and also score fresh propaganda victories,” said Otto. “An attack in Europe has instant, global impact.”

Unlike other terrorist groups, ISIL has little consideration for repercussions from attacking the West due to an apocalyptic narrative that foresees a final showdown with the enemies of Islam, said Brian Michael Jenkins, adviser to the president of the RAND Corporation.

“There is a huge emphasis on end-of-times language with ISIS,” he said. “Even though there is increased danger, and a high likelihood of being killed, you have to be there for the final battle, wherever it may be.”

Means to the ways

ISIL has long impressed Western observers with the sophistication of its state-like organization. To support its efforts abroad, experts said the group was very likely applying a similar, systematic approach, relying heavily on a cadre of highly trained, former Iraqi intelligence officers.

In a threat assessment report published in January, the European intelligence agency Europol wrote that ISIL had likely equipped itself with an “external actions” command devoted to organizing commando-style operations abroad. Europol also noted the existence of small-scale training camps in the EU and Balkan countries, where potential fighters learn survival skills essential for protracted standoffs with law enforcement.

On top of that, Moniquet said that the terrorist group had probably already dispatched a small cadre of determined jihadis to Europe, where they would recruit operatives for the next attack. The approach echoes that used by Paris attacks coordinator Abdelhamid Abaaoud, who traveled back and forth between Syria and Belgium several times to set up a cell of "sleepers."

"These are people who would be exceptionally well-trained, Iraqi or Syrian nationals, less than 10 people, and active at the level of conceiving or organizing operations," said Moniquet.

If such a group does exist, its members would have access to a wide pool of potential recruits in Europe. France alone counts some 1,800 people involved in jihadist "networks," Paris prosecutor François Molins said in January, referring to people who have either traveled to Syria, planned to go or are in transit.

In the country that has provided more volunteers for Syria than any other in Europe, there is an even wider category of "radicalized individuals" whose number is estimated at 8,250, according to a Le Figaro report last month. (The group includes people whose suspicious behavior has prompted a tip-off to police.)

While locals are a concern for police, authorities say returned fighters are more likely to carry out big attacks.

According to U.S. intelligence estimates cited by terrorism experts, nearly 2,000 fighters have returned to Europe after stints in Iraq and Syria, out of some 5,000 who left in the first place.

The estimate appears to be conservative, given that it reflects numbers provided by national governments. By definition, that excludes anyone who evaded authorities' attention on their trip home.

Europol found "no concrete evidence" terrorists infiltrate Europe via refugee flows, but Islamist recruiters target refugee centers.

Whether this flow was growing or shrinking as a result of the coalition bombing campaign remained unclear, however.

"We believe that the flow of fighters from Europe to ISIL, since it began, has diminished," said the RAND Corporation's Jenkins. "We know that some are departing for other fronts, such as Libya, and some are returning home, but the reports are anecdotal, and authorities may not be aware of everyone returning to Europe."

"There is a number that we don't know about," Jenkins said.

In its videos, ISIL still urges members to stay and fight for the Caliphate while berating those who leave, he added. For those who do manage to leave, the closure of Syria's border with Turkey has made the trip home more difficult than it was six months ago, while European authorities are on alert to detect returning fighters.

Refugee flow path?

The question of whether terrorists are trying to infiltrate refugee flows into Europe is political dynamite, hotly debated ever since Syrian travel documents were found near the body of a November 13 suicide bomber.

In its threat assessment, Europol said there was "no concrete evidence" that terrorist travelers systematically tried to infiltrate Europe via refugee flows. However, it did note reports that refugee centers were being targeted by Islamic extremist recruiters.

Hans-Georg Maassen, the head of Germany's internal security service, warned in January that terrorists were slipping into the country "disguised or camouflaged as refugees."

Underscoring the concern, a Syrian former jihadist in Germany was arrested in January. The man, 24, is suspected to have belonged to Jabhat Al Nusra, the Syrian branch of Al Qaeda, and participated in the kidnapping of a United Nations worker.

While authorities fear an attack by trained ISIL operatives, they say the threat of a major event does not replace the pre-existing threat of small-time, lone-wolf attacks.

Instead, terrorism experts said that it adds a new layer to the overall threat profile, with small-scale attacks likely to continue in order to keep authorities on edge — and spending heavily on security — in between major operations.

French criminologist Alain Bauer said that despite the apparent sophistication of the November 13 attacks in Paris, terrorists were likely to keep carrying out amateurish strikes that require little coordination or planning.

"Hyper-terrorism is dead," he said. "It existed on 9/11, in the U.S. embassies, in London and in Madrid — then it ended. The means are too complicated, it's too difficult to coordinate, the risk of being thwarted is too high."

Despite the November 13 attacks, which originated with a specific Belgium-based cell, terrorist groups now largely rely on local actors to respond to propaganda and carry out attacks without guidance or support from abroad. "It's not very complicated to operate a kalashnikov, or a meat cleaver," Bauer said. "That's still the era we are in now, even after November 13."