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For three years, terrorists controlled a huge stretch of territory in Iraq and Syria. They ran their own state, collecting tens of millions of dollars in taxes and using the proceeds to fix potholes, issue birth certificates, finance attacks and recruit followers from around the world.

All but 1 percent of that territory is now gone, which has prompted the White House to describe ISIS as “wiped out,” “absolutely obliterated” and “in its final throes.” But to suggest that ISIS was defeated, as President Donald Trump did when he announced plans to pull U.S. troops out of Syria, is to ignore the lessons of recent history.

The group has been declared vanquished before, only to prove politicians wrong and to rise stronger than before.

The attack last week by a suicide bomber outside a ­shawarma restaurant in Manbij, Syria, which killed at least 15 people including four Americans, is one example of how the group still remains a serious, violent threat.

“People make the mistake of thinking that when you lose territory, it’s linear — that they will continue to lose,” said Seth G. Jones, a senior adviser at the Center for Strategic and International Studies and the author of the center’s recent study assessing ISIS’ troop strength.

“When you lose territory, smart groups shift to guerrilla strategy and tactics, including targeted assassinations, ambushes, raids, bombings,” he added. “That is how you wear the enemy down.”

Trump’s declaration that ISIS has been defeated is the second time the group has been described this way.

A decade ago, the group had been pummeled so hard that officials estimated it was down to its last 700 fighters. Over one 90-day period, U.S. forces arrested or killed 34 of the group’s top 42 leaders.

With his troops exhausted and outnumbered, the emir of the terrorist group privately lamented that they could no longer hold ground.

“We now have no place where we can stand for even a quarter of an hour,” the emir, Abu Omar al-Baghdadi, is said to have told his deputies, according to the group’s own account of the period before the U.S. troop withdrawal from Iraq was completed in 2011.

But after that withdrawal, the group rapidly rebuilt itself, and just four years later, succeeded in seizing a territory the size of Britain.

Recent estimates indicate that ISIS has more than 20 to 30 times the fighters it had the last time it was left for dead.

Although many of its leaders have been killed, the group’s caliph, Abu Bakr al-Baghdadi, and several of his top deputies, are believed to be alive.

But the crumbling of the state has made it difficult to recruit and only a trickle of new members are believed to still be heading to the region from overseas, down from the thousands that were crossing into their territory before.

Meanwhile, attacks have dropped in certain critical locations, like Iraq. That doesn’t mean the group doesn’t remain lethal there. In 2018, in the months after Prime Minister Haider al-Abadi declared victory over ISIS, the group carried out more than 1,200 attacks just in Iraq, according to one data set.

Also, the group’s acolytes continue to kill around the world, including last month in one of Europe’s Christmas markets, in Strasbourg, France, where a gunman who had left a pledge of allegiance to ISIS on a USB stick killed five people, and on a trail in Morocco’s Atlas Mountains, where a group of men who also had recorded a pledge killed two Scandinavian ­tourists.

With the attack on the Syrian restaurant, the world was again reminded of the group’s ability to carry out deadly attacks.

Two U.S. troops were killed in that suicide bombing, doubling the death toll for U.S. forces killed in combat since the start of their four-year deployment to Syria.

“Everyone knows, and we have always said, that the battle against ISIS has not ended, the danger of ISIS has not ended,” said Shervan Darwish, spokesman for the Manbij Military Council, where the attack occurred. “ISIS still has power, still has cells and it is working to reorganize its ranks.”

Experts said the White House is mistakenly equating the group’s shrunken territorial holdings with its overall strength. From its peak four years ago, when it held nearly half of Syria and a third of Iraq, ISIS has now lost all but a fraction of the land it once held in the region.

But it has made a tactical shift to a guerrilla strategy, as Jones of the strategic and international studies group described it.

ISIS announced this tactical shift as early as 2017, in an article in Naba, its weekly newsletter.

Michael Knights, a senior fellow at the Washington Institute for Near East Policy, documented how throughout Iraq the group has focused with laserlike precision on killing “moktars,” or village chiefs, as well as tribal elders and local politicians.

These targeted assassinations drew little coverage in the international news media, and yet they have helped undercut the trust Iraqis place in their government’s ability to protect them — as well as drive young men back into ISIS’s fold, Knights said. “If ISIS can come to your town and kill the most important person in your town any night of the year, do you feel you’ve been liberated?” he asked.

It is in that context that analysts are viewing the deadly attack last Wednesday on U.S. forces in Manbij.

“To conduct an attack like this means that ISIS was conducting intelligence and reconnaissance on the movement of U.S. soldiers and had someone pre-positioned in the city so that once they got info on timing and location they could get someone on the site pretty fast,” said Jones of the strategic and international studies group. “That means that in Manbij, they have a cell structure.”