Islamic State fighters who fled into the desert to escape U.S.-backed forces in Syria and Iraq are now drawing on stashed weapons and ammunition to stage renewed attacks in both countries, as friction among foreign powers hampers efforts to finish the terror group off.
The attacks are a sign of Islamic State's advance planning, and they have complicated the Trump administration's plans to withdraw U.S. troops. Before retreating from its urban strongholds, Islamic State decentralized its command structure, set up sleeper cells, and dug tunnels in the vast desert that spans the two countries.
The Pentagon now no longer gives a timeline for wrapping up a campaign that the White House said in April was coming to a rapid end. The U.S. currently keeps approximately 2,000 troops in Syria.
"Our military campaign in Syria continues," Defense Secretary Jim Mattis said last month. A Trump administration proposal to replace the U.S. contingent with Arab forces--to be largely funded by Arab states--has made little headway.
Islamic State is able to hang on in part because of conflicting priorities among the many local and foreign troops fighting in Syria. Iranian forces patrol parts of the Syrian desert where Islamic State hides, and where Russia has conducted airstrikes, but both powers are primarily preoccupied with battling other, larger insurgent groups to ensure the survival of the Syrian regime.
And earlier this year U.S.-backed Kurdish fighters withdrew from the anti-Islamic State campaign after Turkish forces crossed the border in January to seize parts of northern Syria that had been captured by the Kurdish YPG militia, which Ankara considers a terrorist group.
"For whom is Islamic State the number one priority? It's only really for the United States," said Christopher Phillips, a Syria expert with Chatham House, a London-based think tank.
The U.S. has been going after what is seen as the largest remaining pocket of Islamic State fighters--believed to number at least 1,000--in the oil-rich eastern Syrian province of Deir Ezzour. Since launching what it calls Operation Roundup in May, the U.S.-led coalition has regained about 20 square miles in Deir Ezzour, according to Col. Sean Ryan, a spokesman for the U.S. military. In May, the U.S. conducted 225 airstrikes on Islamic State positions--three times as many as in March, most of them in or around Deir Ezzour.
But while the coalition has focused on an area east of the Euphrates River along the Iraqi border, Islamic State has a presence in another area west of the river. And that area falls outside the coalition's area of control as outlined in a deconfliction agreement with Russia.
Islamic State's recent attacks have targeted an array of adversaries, including both U.S.-backed fighters and rival groups. On July 3, the group claimed its first attack in Raqqa since it was ousted from its former de facto capital in Syria last October: an attack it said took place the day before on U.S.-backed Kurdish forces outside a mosque. The attack followed another bombing on the city's outskirts on June 22. Both attacks were confirmed by local antigovernment activists.
Late last week, a U.S. military convoy hit a roadside bomb in Deir Ezzour, according to the U.S. military, which said there were no casualties. Islamic State claimed responsibility for the attack.
Militants with the group also killed scores of Iranian-linked forces in attacks on their positions in the eastern Syrian province of Deir Ezzour last month. The dead included militiamen from Iraq and Hezbollah fighters from Lebanon, and at least one Islamic Revolutionary Guard Corps commander from Iran, according to semiofficial Iranian media.
In northern Iraq, meanwhile, Islamic State has carried out a spate of attacks, from abducting shepherds to ambushing and killing truck drivers belonging to pro-government tribes. Last week, the bodies of eight men kidnapped by Islamic State were found dumped north of Baghdad with marks of torture.
Islamic State's survival strategy was long in the making. Months before being ousted from Raqqa and Mosul, the Iraqi city the group lost control of last summer, Islamic State began preparing to use the desert as a base to fight regime and foreign forces.
"Now, the group is trying to activate this contingency plan," said Haid Haid, research fellow with the London-based International Center for the Study of Radicalization and Political Violence. "They are trying to increase attacks to stay relevant."
U.S. military officials said they don't fear a resurgence of Islamic State because its gains over the past couple of months have been confined to ungoverned desert.
Fears that fleeing Islamic State fighters would ramp up attacks in the West after losing Mosul and Raqqa have so far not become reality. Of the 1,500 or so Europeans who went to fight for Islamic State, at least 1,200 have returned to their home countries, according to the European Union.
The bigger concern, the U.S. military officials said, lies in fissures emerging among U.S.-backed forces in Syria. The Assad regime is trying to undermine faith in those U.S.-backed forces by sowing discord between them and local residents who are returning to places like Raqqa, the U.S. officials said.
Analysts warn any substantial U.S. drawdown could presage the group's return. The Trump administration's stance on troop presence in Syria is difficult to predict, they say.
"There is a very real possibility that, in the future ISIS or an ISIS equivalent would take advantage of the poor governance in the Kurdish areas," where the Americans currently fight the group, said Mr. Phillips of Chatham House.
The group's leadership has used also its networks in Syria and Iraq to fund and otherwise support various affiliates beyond Syria, according to U.S. intelligence officials.
Islamic State has stepped up attacks in Afghanistan and Somalia, and its Sinai Province affiliate in Egypt has grown more brazen, killing more than 300 people in a mosque attack last November. Egypt's President Abdel Fattah Al Sisi has expressed concern that Islamic State fighters from Iraq and Syria would flee to Egypt.
And in mid-June, as Syrian regime forces redeployed from the province of Suweida to take part in an attack on antigovernment rebels in neighboring Daraa, Islamic State occupied more territory in the area.
"It's an impossible mission to finish ISIS in the desert," said Fadi Dahouk, a local journalist from Suweida, referring to another name for Islamic State.
During its rule, Islamic State militants imposed harsh punishments on people who violated their strict Islamic dress codes and smoking bans. In towns around places such as Deir Ezzour and Raqqa, locals say that some people still abide by these rules because they fear the insurgents may soon return.