A long-anticipated bid to recapture the Iraqi city of Ramadi from the Islamic State has gotten off to a slow start, with sectarian tensions already hampering the Baghdad government's offensive. The fall of Ramadi to Islamic State extremists in May delivered a humiliating blow to the fragile government of Prime Minister Haider al-Abadi and cast doubts on the U.S.-led coalition's war strategy. Iraqi leaders since then have repeatedly vowed to take back the city as well as the rest of western Anbar province, and a broad operation pitting 10,000 Iraqi troops against the 200-300 Islamic State fighters estimated to be in the city finally got underway on July 13. American and coalition warplanes have bombed ISIS positions throughout the city in support of the Iraqi push. But initial signs indicate no quick victory is in the offing for Iraqi security forces and that Sunni-Shiite rivalries are once again potentially jeopardizing the campaign, senior U.S. and coalition officers said Saturday. "I think it's fair to say that progress has been steady but difficult," British Brigadier James Learmont, deputy commander of the coalition mission to train and advise Iraqi forces, said in a briefing in Baghdad. Learmont said it was too soon to make any forecasts about how long the offensive might last even though the number of Iraqi forces is exponentially larger than the number of Islamic State fighters. Plagued by poor morale and crippled by the country's sectarian and ethnic politics, the government army has a notoriously feeble track record. Often derided as a "checkpoint army" that prefers to stay put, Iraqi forces have scored only a handful of successes since they were routed by Islamic State militants last year across a wide stretch of territory. At the moment, Iraqi forces — including army and police units — are trying to "isolate" Ramadi and cut it off from supply routes linked to nearby Fallujah, Learmont said. In the first days of the operation, U.S. and coalition warplanes hit Islamic State positions with dozens of airstrikes around Ramadi to back up Iraqi forces, officers said. But over the past two months, Islamic State fighters had time to build up extensive defenses, setting up gun positions along berms and planting belts of homemade explosives on the approaches to the city. Iraqi officials had announced a counterattack in May in Anbar province but that proved to be overly optimistic, and a full-scale offensive is only starting now. Abadi's government had initially planned to try to retake the northern city of Mosul, Iraq's second-largest, around June but delayed that offensive in order to focus on Anbar. Setbacks in the war against the Islamic State have prompted calls in Washington for expanding the U.S. military's role by having the American special forces troops training the Iraqi military accompany those soldiers into combat and help direct bombing raids. The U.S. military's top officer, Gen. Martin Dempsey, who flew to Baghdad Saturday to confer with senior coalition commanders, said he posed the question to fellow officers but the idea was rejected. "I asked the senior leaders point blank: ‘Are we at the point where, in order to make sure this mission succeeds, that we need to be here in greater numbers and go farther forward?'" Dempsey told reporters traveling with him. "And the answer was ‘no.'" Dempsey's brief visit to Baghdad came a day after one of the most deadly attacks ever orchestrated by the Islamic State group. At least 115 people were killed in Khan Bani Saad in Iraq's Diyala province on Friday when a suicide bomber with an ice truck detonated a massive explosive in a crowded market. Dempsey, who served in Iraq as a commander for two tours, said officials inside the Iraqi government had an "internal debate" about which forces should take the lead and which city held by the jihadists should be targeted first. Some officials had favored moving to recapture Fallujah first before focusing on Ramadi, Dempsey said, with the disagreement underscoring divisions about the relative roles of Shiite militias — most of which have ties to neighboring Iran — and Sunni tribal fighters in those planned operations. In a compromise, Iraqi leaders agreed to target Ramadi first with government security forces at the forefront while Shiite militias would stage a blocking action on the outskirts of Fallujah to choke off key supply lines, Dempsey said. And he said the plan calls for Sunni tribal volunteers — who only recently began receiving training and arms from the U.S. — to deploy to Ramadi after the city is cleared to "hold" recaptured areas. American officials hope the presence of Sunni fighters, rather than Shiite ones, will help reassure the local Sunni population. Dempsey, in what is expected to be his last trip to Iraq as chairman of the U.S. Joint Chiefs of Staff, said there was a clear power struggle underway between Shiite militias and Iraqi government forces. "I believe over time the Iraqi security forces will reassert themselves," said Dempsey, predicting that success on the battlefield will make them "the viable force of the future." But, he said, "in the meantime, there is a competition" between the army and the militias. Dempsey also acknowledged that he felt some "disappointment" with the Shiite-led Baghdad government for its handling of the war and the country's alienated Sunni population. "I've been disappointed at the pace of some of the necessary legislative initiatives, some of the decision making, some of the leadership changes, some of the disagreement in the Iraqi political structure . . ." he said. Still, he praised Abadi for pushing to arm Sunni volunteers, especially since he said the Iraqi leader had encountered resistance from others in his own government. "There was a period there where, although the prime minister said to do something, getting it accomplished at the depot level was a bit of a challenge," he said. Abadi's orders eventually were carried out and "the arms, the ammunition, the equipment, the support is flowing" now to the Sunni fighters in Anbar, Dempsey said. With the end of the holy month of Ramadan, Dempsey said he expected the pace of the operation around Ramadi to pick up. Success is far from guaranteed, however, and U.S. involvement in the campaign could be constrained because of unease about Iran's de facto leadership role in the push. The presence of Iranian-backed Shiite militias is causing serious concern in Washington, amid fears the fighters could aggravate the country's sectarian divide and provide Tehran with decisive influence in the country. Dempsey reiterated that U.S. aircraft would not carry out bombing raids in support of Shiite militias in the Popular Mobilization Front, or PMF, that are not strictly under Baghdad's control. "We've been crystal clear that we are not going to provide our support to the PMF because it's a non-state or a sub-state actor," Dempsey said. Brig. Gen. Yahya Rasool, spokesman for the Iraqi Defense Ministry, defended the tempo of the offensive near Ramadi and said bridges and other key areas had been seized on the outskirts of the city this week. He said the operation was being carried out in a deliberate manner to avoid civilian deaths or unnecessary damage to the city's infrastructure. "We are not in a hurry," Rasool said. Despite an edge in manpower, air power and weaponry over the Islamic State, the Iraqi army has often faltered or gotten bogged down when battling the jihadists. The Iraqi military has recurring leadership and organizational problems, and after Ramadi fell two months ago, Defense Secretary Ash Carter said the government troops who fled had lacked the "will to fight." But coalition military officers said the Iraq security forces were now ready to confront the Islamic State in Ramadi. "We're seeing an Iraqi will to fight and we're seeing momentum that perhaps a few months ago would have been lacking," Learmont said.