IRBIL, Iraq — The Iraqi military had planned on a big celebration Saturday, the third anniversary of the Islamic State's capture of Mosul, by completing the liberation of Iraq's second-largest city and the militants' last major stronghold in the country. But it didn't happen.
Instead, the military is still struggling to eject a militant group that has shown renewed determination and ferocity than expected despite being heavily outnumbered.
On Sunday, Iraqi forces began to storm one of the gateways into the final bastion held by the Islamic State, or ISIS, in Mosul: the "Old City."
"They are fighting much harder than before," said Rebin Rozhbayane, a former officer and trainer with the Iraqi army who was near the front lines in western Mosul over the past few weeks.
Iraq's Joint Operations Command said Sunday that 23 militants were killed as government troops entered Bab Sinjar, the northern entrance to the Old City. Fewer than 1,000 fighters are believed to remain in Mosul, hiding among hundreds of thousands of civilians. Tens of thousands of Iraqi troops are deployed to dislodge the militants.
Yahya Rasol, an Iraqi military spokesman, said the army's Ninth Division took the Zanjli neighborhood north of the Old City, allowing Iraqi forces to control the Bab Sinjar entry.
Iraqi federal police posted on their official Facebook account that they are "tightening the noose" around ISIS in the Old City, which has been completely encircled by government forces. Iraqi forces captured eastern Mosul in January and later crossed the Tigris River into western Mosul, where the ancient city first arose.
Liberating the Old City is the most difficult part of the offensive because of its narrow streets and densely clustered buildings. These conditions prevent the use of armored vehicles and create a high risk of ambushes, booby traps and civilian casualties.
The big prize in the Old City is the al-Nuri mosque, where ISIS leader Abu Bakr al-Baghdadi made a public speech in 2014 after the militants captured Mosul. Recapturing the city would mean a symbolic end to the Islamic State's reign in Iraq.
Iraq's federal police forces came within hundreds of yards of the mosque in March and hinted at the time that they would take it shortly. However, the widely publicized deaths of hundreds of civilians in U.S.-led bombing raids forced a change in strategy.
Iraqi forces decided to surround the Old City first and then open corridors for civilians being used as human shields to escape. "The biggest challenge is to kill the (ISIS fighters) while making a safe way out for civilians," said Muntader Khazem, a sergeant with the Emergency Response Division, the elite unit of the federal police.
According to Rozhbayane, the presence of civilians is slowing down the operation, even though U.S. Air Force Col. John Dorrian predicted in May that ISIS is "on the brink of total defeat in Mosul."
Rozhbayane said Iraqi forces are now proceeding more cautiously, taking many breaks to update their tactics and give their troops time to rest.
The United Nations refugee agency reported on Thursday a "significant escalation of extremist groups’ use of civilians as human shields and targeting of those attempting to flee areas under their control."
"At least 204 civilians attempting to flee western Mosul have reportedly been killed during the last week alone," the refugee agency said.
In addition to worries about trapped civilians, the Iraqi offensive has slowed because of fierce resistance from ISIS fighters who have nowhere left to go. A handful of snipers holding out in a single building were enough to delay Iraqi forces by up to a day.
"The last thing you want to do is underestimate these guys," said Alex Moreau, a Canadian forces veteran serving as a volunteer medic near Mosul. "Some of them have been fighting since the early days of the American occupation" in 2003, said Moreau, who said he saw scores of federal police casualties.