SOUTH OF MOSUL, Iraq (AP) -- U.S. Army Lt. Col. James Browning juggled phone calls on an overstuffed sofa in a small village south of Mosul. His counterparts in the Iraqi army's 9th Division were pushing toward western Mosul, just a few miles away and were coming under mortar fire from the Islamic State group as they moved on a power station.
Iraqi army Brig. Gen. Walid Khalifa called Browning on a simple Nokia phone to relay the approximate location of the mortar fire. Browning swapped phones to make another call.
"Can you tell them that (the 9th Division) is receiving fire?" he told his coalition colleagues at another forward base overseeing the operation. He asked them to pinpoint where the attack was coming from using coalition aerial surveillance and take it out.
Just a few months ago, Lt. Col. Browning's phone conversation would have been impossible. Rather than request assistance directly, his call would have likely been routed through a joint command center much farther from the battle zone.
In the fight against the Islamic State group in Mosul, the United States has adjusted its rules of engagement as American and other international troops are now closer to front-line fighting than before.
During the push to take Mosul International Airport on Thursday, American and European advisers were embedded with forward Iraqi rapid response and special forces units.
Coalition officials say the changes are helping speed up Iraqi military gains, but they mark a steady escalation of U.S. involvement in Iraq that also reflects lingering shortcomings on the part of Iraq's armed forces and growing political and military pressure to finish the Mosul operation quickly.
"Usually I'm right by his side," Browning said between phone calls of his Iraqi army counterpart Brig. Gen. Khalifa. "When a threat comes in like this, we take it just as seriously as if we are under threat."
This closer relationship is new.
In the lead-up to the operation to retake Mosul, U.S. forces steadily increased their footprint in Iraq, increasing the number of troops in the country and moving outposts closer to front-line fighting. But the number of U.S. forces on or near the front lines remained relatively small.
Two months into the campaign to retake Iraq's second-largest city from IS control, Iraqi forces appeared bogged down by weeks of grueling urban combat. Some front lines went stagnant for weeks and Iraqi forces were suffering relatively high casualty rates under fierce IS counterattacks.
On Dec. 26, U.S. Army Lt. Gen. Stephen Townsend issued a tactical directive sending more coalition troops away from the safety of their outposts, deeper into Mosul and closer to front lines to work side by side with their Iraqi counterparts. In January, the Pentagon first confirmed that U.S. forces were at times operating inside the city of Mosul.
As Iraqi special forces and rapid response units stormed Mosul's airport and the sprawling Ghazlani base on the southern edge of the city's west, coalition forces were embedded with forward units advising them on their plan of attack, according to two Iraqi officers overseeing the operation. The officials spoke on condition of anonymity as they were not authorized to talk to reporters.
Inside eastern Mosul, in the weeks leading up to that half of the city being declared "fully liberated," coalition troops became a more common sight on the city streets alongside Iraq's elite military units.
"It changed the relationship," Browning said of moving closer to the front and spending more time with his Iraqi counterparts. "It gives me a better understanding of how I can bring to bear the limited capabilities I have."
During his Thursday interview, Browning spoke from a modest forward Iraqi base in a small village south of Mosul where a living room in an abandoned home had been converted into an operations room.
Under the December directive and an additional directive issued a few weeks ago, Browning said advisers like him embedded at the brigade level are now able to directly deliver support such as airstrikes and artillery fire to the units they're partnered with.
Previously, such support "would have gone through a whole bureaucracy and through Baghdad," he said.
The spokesman for the U.S.-led coalition, Air Force Col. John Dorrian, confirmed to The Associated Press the rules of engagement in the fight against IS in Iraq were adjusted by the December directive, explaining that some coalition troops were given the "ability to call in airstrikes without going through a strike cell."
More coalition forces have been "empowered" to have the ability to call in strikes in the Mosul operation, Col. Dorrian told a Pentagon press briefing on Wednesday.
"This is something that maintains a very high level of precision, but it also increases the amount of responsiveness for the teams on the ground," he said.
Since the late December directive from Lt. Gen. Townsend, Iraqi forces have secured swifter territorial victories in the fight against IS and in the first days of the renewed push on Mosul's western half, Iraqi forces have sustained relatively low numbers of casualties, compared to the early days of the fight inside Mosul from the eastern front.
"There was a lot of focus on a big training effort and I think what (the coalition) realized in Mosul is that (Iraqi security forces) needed more tactical support," said Nathaniel Rabkin, managing editor of Inside Iraqi Politics, a political risk assessment newsletter.
Iraqi and coalition forces are coming under increasing political and military pressure to wrap up the fight for Mosul quickly. Lt. Gen. Townsend has repeatedly said he wants the operations for both Mosul and Raqqa to "conclude" within the next six months.
The Iraqi and American leadership is concerned the humanitarian situation in western Mosul could quickly deteriorate, Rabkin said, and that infighting could break out within the "fragile" coalition of anti-IS forces, including Shiite militias, conventional Iraqi military forces and Kurdish fighters.
"You want to finish this while there is still good will," Rabkin said.