The Iraqi security forces’ seemingly inexorable push toward Mosul saw fighting begin in the city itself this week, but it is work taking place in the skies above that has enabled such dramatic advances.
A relentless air operation using planes and drones from a dozen or so members of a US-led coalition against the Islamic State group has over more than two years conducted some 16,000 air strikes against the militants in Iraq and Syria – two-thirds of them in Iraq.
Mostly, coalition planes conducted “deliberate” strikes, where they destroyed targets acquired through intelligence or surveillance.
“Now, it’s almost entirely dynamic strikes,” a US military official told reporters during a recent visit to the Combined Air Operations Center (CAOC), from where flights over Mosul and elsewhere are co-ordinated.
Dynamic strikes occur when ground units need air support on an unexpected target, such as an enemy fighting position or a car bomb being driven across the desert.
“The operation in Mosul is the number one priority right now,” another US military official said.
Consider air activities in and around Mosul for just one day.
On Wednesday, coalition planes destroyed an IS headquarters building, five storage containers, two mortar systems, two fighting positions, a bomb-making factory, a supply cache, a sniper position, an observation post and a culvert.
The strikes also engaged two tactical units and damaged two tunnels, a bridge and a supply route, according to the coalition.
The coalition has enjoyed total air superiority in its anti-IS campaign.
While planes have come under sporadic small-arms fire, the most significant damage was when a C-130 cargo plane took three bullets to its tail.
Officials worry militants might seize “prestige” weapons such as surface-to-air missiles in the chaos that is neighbouring Syria, but so far this threat has not materialised.
Lacking military means, IS fighters use civilians trapped in Mosul as human shields to prevent strikes.
The cost of the operation to date is almost $10bn.
At any given time, 15-20 coalition aircraft – mostly drones – circle Mosul, creating a green “donut” on radar screens that pinpoint each plane’s location with a small icon.
Russian planes, which operate in the same air space over Syria, are yellow.
The centre is the primary hub for anti-IS air operations and coalition intel, and a never-ending stream of video from drones is beamed across eight huge monitors covering most wall space in the cavernous operations room.
One feed shows a small white pickup truck somewhere in Iraq.
The drone’s eye follows the vehicle into a compound, where a man loads something into the back.
The drone is 10,000ft (3,000m) above but the footage is so clear he can be seen tucking his white shirt into his pants.
The man’s fate is unclear; a military official said he was likely an IS fighter.
Even as the Mosul fight rages, officials are looking over to Raqqa in Syria as the next step in the campaign.
Like they did in Mosul, the coalition has started hitting targets to “soften” areas in and around the city ahead of an assault.
Iraqi security forces approaching Mosul grew accustomed to continual coalition air cover.