Iraqi security forces are advancing in Mosul and could defeat ISIS in the country "within three months," said Iraq's Prime Minister Haider al-Abadi. The prime minister made his remarks Tuesday in a Baghdad press conference that was broadcast on Iraqiya State TV. His comments came as Iraqi forces prepare for the next phase of military operations in its fight to wrest the city of Mosul from ISIS control. Since October, a coalition of Iraqi-led forces including the Iraqi army, counter-terrorism forces, federal police, Kurdish Peshmerga fighters and Shiite-led paramilitary forces have pushed to end ISIS' brutal rule in Mosul. The city remains the last major stronghold of ISIS after the militant group seized control in 2014. What began as a rapid push into the city in early November has turned into a block-by-block war, with ISIS inflicting high casualty rates on advancing Iraqis. Security officials told CNN that ISIS' vicious tactic of using civilians as human shields is slowing down the advance of Iraqi troops in eastern Mosul. Mosul surrounded by Iraqi forces Iraqi forces have accomplished its goals for the first phase of its Mosul military operations, Iraqi Ministry of Defense spokesman Brig. Gen. Tahsin Ibrahim told CNN on Wednesday. These goals consist of surrounding Mosul and recapturing most towns and villages around the city. Some 100,000 troops have converged simultaneously around Mosul. The second phase of the operation is to continue liberating neighborhoods in the eastern and western sides of Mosul from ISIS, protect civilians and provide safe routes for the civilians who wish to leave, Ibrahim said. "The second phase will witness changes in the military methods of fighting ISIS in Mosul and especially after Iraqi troops gained good experience of fighting them there in the past weeks," Ibrahim said. "Iraqi troops can't use artilleries and tanks in the streets of Mosul and thus these things would slow down the advances of our security forces. We are now facing significant challenges due to the presence of civilians but we will continue until we liberate the entire city." Meanwhile, Iraqi's prime minister said there are no plans to have US combat troops to fight along with Iraqi security forces, calling such media reports "an outright lie." "There is not a single foreign soldier fighting on the Iraqi soil," al-Abadi said. "Foreign troops are here for only training and logistics purposes." Last bridge over Tigris On Monday, a US-led coalition airstrike disabled the last functioning bridge over the Tigris River in Mosul that had linked the city's east to west. The Old Bridge was the last one remaining over the Tigris River. The US-led coalition confirmed the damage in a statement released Wednesday, but didn't provide additional details. ISIS' media wing, Amaq, posted a video showing the collapsed section of that bridge, also known as "Old Bridge" and the "Iron Bridge." It had been the last one standing in Mosul over the Tigris River after four others were damaged in coalition airstrikes in the past two months. A Google Earth satellite images of bridges across Mosul's Tigris River before the operation. Taking out the bridges enables Iraqi-led forces to contain ISIS fighters and cut off their supplies and access to reinforcement fighters. But it also restricts the movement of civilians. The International Organization for Migration had expressed concern that taking out the key bridges would trap civilians inside Mosul after the fourth bridge had been damaged in a US airstrike in late November. Civilians caught in the middle The human toll in Mosul has been significant with more than 114,000 people displaced from their homes, according to UN Office for the Coordination of Humanitarian Affairs (OCHA). "As many as one million people are estimated to remain out of reach of humanitarian assistance in Mosul city. Of particular concern are reports of food and water shortages" the UN said in a statement released last week. Trauma injuries among civilians are a significant concern in eastern Mosul city with 973 injuries reported last week, mainly from gunshots, mines and indirect fire, according to the OCHA statement. Aid organizations say they fear the fighting could result in the displacement of more than a million people. A number of groups are helping families displaced by the war.