BAGHDAD — The graffiti that appeared on a wall near the mosque in Mosul where the Islamic State leader declared his caliphate two years ago was a small but symbolic act of rebellion.
The spray-painted letter “m” — for the Arabic word “mukawama,” meaning resistance — was part of a campaign by Kitaeb al-Mosul, an underground opposition group in the northern Iraqi city that released a video detailing their efforts this month.
The Islamic State reacted with swift brutality, executing three young men it accused of being involved. The militants released their own video showing the men kneeling in orange jumpsuits before being shot in the head. The letter “m” was sprayed on the wall behind them, a reference to their alleged crime. A spray can lay on the ground beside them, surrounded by blood.
In recent months, the Islamic State has carried out more arrests and executions such as these in a sign of desperation as it faces the prospect of losing Mosul, according to reports from inside the city.
Mosul is the largest city under Islamic State control and is central to its narrative of having restored the Islamic caliphate. It was less than a month after Mosul fell in June 2014 that Abu Bakr al-Baghdadi appeared in the mosque there and called on Muslims to follow him.
The recapture of the city would be a significant step toward depriving the Islamic State of its territory and forcing the group back into an insurgency, U.S. and Iraqi officials say. That is only a matter of time, they add.
Prime Minister Haider al-Abadi has pledged to retake Mosul by the end of the year, and the Iraqi air force dropped 7 million leaflets on the city last week telling residents to prepare for the “zero hour.”
As Iraqi forces — and the U.S. troops advising them — move closer, making the recently recaptured Qayyarah Air Base, 25 miles south of Mosul, a logistical hub for the impending battle, the Islamic State has also been making preparations.
“Daesh is weaker in Mosul, but it is using methods of oppression like random arrests to try and show it is still in control,” said a representative of Kitaeb al-Mosul. Daesh is an alternative name for Islamic State. He spoke on the condition of anonymity for security reasons. He described the atmosphere in the city as “tense” and said the militants were in a state of “confusion.”
The Islamic State began carrying out mass arrests after the group began its graffiti campaign two months ago, he said.
The militants have constructed new berms around neighborhoods on the north, east and south sides of the city, he said. In some neighborhoods, concrete barricades have been erected, he said, speculating that the militants are trying to isolate neighborhoods because they are concerned that residents may turn against them if Iraqi forces draw near.
“Right now they are making arrests with no investigation, in a way they didn’t before,” said Sheikh Mohammed al-Jarba, a tribal leader from the city, who said he is regularly in touch with people there.
“I know they are digging new trenches around the city,” he said. “They’ve never stopped digging them.”
Internet connections to homes in Mosul have been banned over the past two months, as the Islamic State attempts to prevent information on its positions from leaking out. Cell networks have been largely cut for more than a year and a half.
However, some patches of phone network remain, and those with relatives in Mosul occasionally receive updates from their loved ones, allowing some glimpses of life in the city.
There are no accurate estimates of the number of civilians that remain in the city, but the United Nations has said more than a million people could flee Mosul and its surroundings during the offensive. Some Iraqi officials and relatives of residents say that figure could be even higher because thousands of people have arrived in Mosul after offensives in other Islamic State areas.
Atheel al-Nujaifi, the former governor of the province, who is now based in the northern city of Irbil, said the displaced had come from areas including Qayyarah, which was retaken by Iraqi forces this month. Some civilians from largely Sunni areas fear how they will be treated by security forces after an area is retaken; others may have sympathies or allegiances to the group or have simply been fleeing the fighting in any direction they could.
Nujaifi said people had arrived from as far away as Manbij in Syria, which was retaken by U.S.-backed rebel forces a month ago.
The presence of a large number of civilians complicates the offensive, which is expected to rely heavily on coalition air support. The Iraqi government and humanitarian aid agencies are also attempting to prepare for a huge exodus but have warned they lack resources.
One former Mosul resident said the Islamic State has been seizing empty homes to house those displaced, including the house of her grandmother who had left the city.
“The number of people has increased a lot,” she said, adding that her friends and relatives had said there had been “searching campaigns” on houses.
“They are paranoid, and the number of searches is way more than before,” said the woman, who now lives in the Iraqi city of Dahuk and whose name has been withheld for safety reasons.
In the same Islamic State video that shows the execution of the alleged spray-painters, the group also executed three men it accused of spying.
“Send your agents and spies; our swords are ready for them and are thirsty for their blood,” a militant said, accusing the men of being “the eyes of America.”
The U.S. military estimates that around 3,000 to 4,500 militants remain in Mosul. Over the past two months, U.S.-led airstrikes have killed 12 Islamic State leaders in Mosul alone, Col. John Dorrian, a spokesman for the coalition, said in a recent briefing.
“These strikes have a disruptive effect on the enemy command and control, which is important in setting conditions for Mosul’s liberation,” he said.
Some officials said people who have collaborated with Islamic State are attempting to switch sides.
“Their own members are trying to deny them,” said Abubaker Kbi, the head of the Sunni Awqaf for Mosul — the official representatives for its mosques. Despite the mosques now being Islamic State controlled, he said he is still in contact with people in the city and has heard from Islamic State members who want to leave.
The former resident said that arrests have also singled out former officers who served in the military under Saddam Hussein.
“They know that they still might have connections to some people in the military, and they are afraid that they will cooperate with the army or turn against them,” she said.
Another resident who fled Mosul but is still in touch with his brother in the city said former officers had been targeted.
One of his distant relatives — a direct relation of a former army officer — had been randomly arrested five days ago, he said.
“All the old officers — they are targeting them and their families,” he said.
Nujaifi said there are also signs of disarray among Islamic State’s ranks, with increasing corruption inside the group. Despite a ban on leaving the city, some residents have been able to escape by paying large bribes.
However, many don’t have the means to do so. For them, it is a waiting game.
“They say even if it means their houses are destroyed, it will be worth it in the end,” the woman in Dahuk said. “They might be weaker, but Islamic State have a strong fist and they are being harsher than you can imagine.”