Iraq's special forces entered the outskirts of Mosul on Tuesday, taking the state television building and advancing despite fierce resistance by Islamic State group fighters who control the city, an Iraqi general told the Military Times.
It was the first time in over two years that Iraqi troops have set foot inside the city, Iraq's second largest.
The advance could be the start of a grueling and slow operation for the troops, who will be forced to engage in difficult, house-to-house fighting in urban areas that is expected to take weeks, if not months.
Troops entered Gogjali, a neighborhood inside Mosul's city limits, and later the borders of the more built-up Karama district, according to Major General Sami al-Aridi of the Iraqi special forces.
Iraqi troops took control of a state TV building on the eastern edge of Mosul and raised the Iraqi flag over it, according to a statement released by Iraq's joint military commands.
An officer with the country's Counter-Terrorism Force told CNN that progress had been slowed by the large number of improvised explosive devices (IEDs) and mines planted by ISIS. He was speaking on condition of anonymity because he is not authorized to talk with the media.
Progress was also slowed by the presence of as many as 20,000 civilians who are still in Gogjali, who are essentially being used as human shields by ISIS, according to Saadi.
Troops are now in clear striking distance of the city and they appear to have begun an assault on Mosul from outside.
Residents of an eastern neighborhood reached by phone said there had been heavy shelling in the area by Iraqi forces, and that they heard outgoing mortars and heavy fire from ISIS machine guns.
Where are the Iraqi forces?
Iraqi army forces entered the Judaidat Al-Mufti area in southeast Mosul on Tuesday, the military announced, while forces from the elite Counter-Terrorism Service retook a village and a local television station on the city's eastern outskirts.
North of the city, soldiers retook several villages as they neared the edge of Mosul, while Kurdish forces have also gained ground north and east of the city in recent days.
The forces on the southern front -- including the Rapid Response Division, CTS's interior ministry counterpart, as well as police -- started the farthest away and have the longest distance still to go, with more than 10 kilometres (six miles) between them and the city.
The Hashed al-Shaabi, an umbrella group for pro-government paramilitary forces that is dominated by Iran-backed Shiite militias, are fighting southwest of Mosul in an operation aimed at retaking the town of Tal Afar, which lies between the city and Syria.
They have gained ground in recent days, but the western approach to Mosul remains largely open for now.
What is the US-led coalition doing?
The US-led anti-IS coalition is carrying out air strikes against the jihadists as well as targeting them with artillery. It has hit IS with nearly 3,000 bombs, missiles, rockets and shells since the drive for Mosul began on October 17.
But some Iraqi commanders have still complained that there are not enough strikes, and said they want the coalition to step up its campaign.
Most of the more than 7,000 coalition military personnel in Iraq are in advisory or training roles, but there are also those carrying out artillery strikes, as well as special forces personnel who have carried out raids against IS.
How are the jihadists responding?
IS has targeted attacking Iraqi forces with suicide bombers, mortar rounds and small arms fire, in addition to bombs hidden in houses, buildings and roads that make up an integral part of the jihadists' defences and still cause casualties even after they withdraw.
Inside the territory they still control, the jihadists are responding with the same brutality that has been the hallmark of their more than two-year rule.
The United Nations said it has received reports that IS has executed nearly 300 people in the Mosul area since October 25, and also seized tens of thousands of people for use as human shields.
IS attempted to transfer some 25,000 civilians from the Hamam al-Ali area south of Mosul to places in and around the city on Monday, but most of the vehicles IS brought were prevented from reaching Mosul because of patrolling coalition aircraft, the UN said.
The jihadists have also staged diversionary attacks in the northern city of Kirkuk and the western town of Rutba in attempts to draw attention and forces away from the Mosul theatre.
How are civilians affected?
As Iraqi forces advance, thousands of civilians have fled IS-held areas to escape both jihadist rule and impending fighting -- a number that could increase exponentially if people leave Mosul en masse.
According to the UN, up to one million people could be displaced by the battle for the city -- a major problem given that existing, under-construction and planned camps can only house about half that number.
The International Organization for Migration said on Tuesday that 17,900 people have been displaced since the operation began.
Displacement is especially difficult for rural farming communities, whose wealth lies in fields and livestock that they cannot take to camps.
The situation for displaced Iraqis will get even more difficult as winter rains and colder weather set in.