In this May 27, 2015, file photo, U.S. soldiers, left, participate in a training mission with Iraqi army soldiers outside Baghdad, Iraq. An array of forces is closing in on the Islamic State’s biggest stronghold in the country, the city of Mosul.Khalid Mohammed/The Associated Press
Almost two years after the Sunni jihadi group known as the Islamic State stunned the world by capturing Iraq's second-largest city, the battle to retake Mosul has finally begun.
An array of forces is closing in on this metropolis, site of one of the world's oldest Christian communities and now the self-proclaimed capital of the IS "caliphate."
From the south, Iraqi security forces along with Sunni tribal volunteers are advancing after their hard-fought success in regaining the city of Ramadi, the capital of the Anbar governorate, and fending off IS counterattacks on Tikrit and Baiji, more than halfway from Baghdad to Mosul.
Also from the south, U.S. Delta Force commandos have staged raids in the Mosul area, including one that the Pentagon says captured a mid-level IS commander from whom they are extracting intelligence. This boots-on-the-ground action represents a shift from the air-only military campaign to which President Barack Obama vowed he would adhere, and may be the thin edge of a wedge of U.S. combat missions.
From the southeast, Iranian-backed Shia militias are proceeding after having cleared IS fighters from towns and villages in central Iraq (and sometimes emptying the places of their civilian Sunni population as well).
Kurdish peshmerga have succeeded in retaking the town of Sinjar, west of Mosul, cutting off the last supply route from Syria, and the Kurds are poised to strike at Mosul from both the east – their Kurdistan base – as well as from the west.
To the north, a number of Turkish armoured forces already are in position on the outskirts of Mosul. Much to Baghdad's consternation, the Turkish forces entered the area in a lightning move in December. Ordered to leave Iraqi territory, the tanks and troops pulled back inside the autonomous area of the Kurdistan Regional Government (KRG), where Kurds apparently have allowed these closely allied forces to remain.
Meanwhile, in the southwest, Saudi forces along with those of 20 Gulf and other local allies are staging a massive military exercise just across the border in Saudi Arabia. The operation, reportedly involving about 150,000 troops, is the largest military activity in the area since the liberation of Kuwait 25 years ago.
The purpose of the exercise – involving 2,500 aircraft, 450 helicopters and 20,000 armoured vehicles – is apparently to send a warning to Iran, and the Iraqi Shia militias that Iran is backing, that the might of this Saudi alliance will come down hard on the Shia forces should they try to drive out the Sunni population around Mosul.
"From the Saudi perspective, Iraq has gone from being the eastern edge of the Arab world, resisting Persian and Shia Iran, to a puppet controlled by Iran," said Bruce Riedel, a Saudi Arabia specialist and director of the Intelligence Project at the Brookings Institution in Washington.
Indeed, there is great unease among the majority Sunni population in the Iraqi governorate of Nineveh, of which Mosul is the capital. In late January, Iraqi Prime Minister Haider al-Abadi announced the coming of the battle for Mosul and explained that Shia militias as well as Kurdish peshmerga forces would be fighting alongside Iraqi government troops.
This was met by outrage from the provincial council that voted against such an alliance being used to liberate Mosul. Mosul residents fear a sectarian conflict if the Iranian-backed Shia militias are involved in the fighting.
The long battle by Iraqi forces to recapture Ramadi from IS fighters provides an indication of just how tough it will be to retake Mosul.
Proceeding house by house and street by street, it took Iraqi security personnel, backed by U.S. and Canadian air strikes, more than five months to gain control of the city, which is a third the size of Mosul.
In addition, IS forces have occupied Mosul for almost two years, more than twice as long as they held Ramadi. That's double the length of time in which to harden the city's outer defences and lay booby traps and landmines throughout the urban area.
The Pentagon has declined to say just when troops will try to enter Mosul, though General Joseph Dunford, chairman of the Joint Chiefs of Staff, said at a press conference Feb. 29 that "it is not something that will happen in the deep, deep future."
For his part, Mr. al-Abadi, the Iraqi Prime Minister, said recently that Iraqi forces would launch a full-scale operation to retake the city as early as March. Military analysts say it's vital to take advantage of the good weather in spring and summer to carry out an attack, since the wet weather of the fall and winter favours the IS fighters.
Whenever it comes, the battle will be far from easy, Major-General Richard Clarke, commander of U.S. land forces in Iraq, recently told reporters. "It's going to be tough."
He outlined two options that ground forces might use for the assault.
One option would be for Iraqi forces to move north from their current positions near Baiji by way of Route 1 that runs up the spine of Iraq and would require the army to fight its way through the Islamic State-held territory along the Tigris River.
The other choice is to "go completely [through] the Kurdistan region," to the east, Gen. Clarke said, which would require Baghdad to reach some kind of political accommodation with the KRG.