U.S. and Iraqi security forces were focused on Mosul in Iraq's northwest, leaving the starving residents of ISIS-held Fallujah a half-hour's drive from Baghdad to wait indefinitely for liberation, according to Obama administration and U.S. military officials.

In a recent briefing to the Pentagon from Baghdad, Army Maj. Gen. Gary Volesky said the 217 additional U.S. advisers and eight AH-64 Apache attack helicopters recently authorized by President Barack Obama for the ISIS campaign would be "tied to the fight for Mosul," although there was no timetable for the offensive.

Volesky, commander of the U.S. Combined Joint Forces Land Component Command in Iraq, made no mention of Fallujah but said that the Iraqis backed by U.S. airstrikes and artillery had advanced to the town of Qayyarah about 20 miles southeast of Mosul. He said that was "the farthest north that Iraqi security forces have been since the fall of Mosul" in June 2014.

Volesky made no mention of Fallujah, which was the scene of fierce street fighting by U.S. Marines in 2004 in which an estimated 95 U.S. troops were killed and another 560 were wounded. The mainly Sunni city, where snipers affiliated with the Islamic State in Iraq and Syria, or ISIS, now prevent residents from fleeing, has been under the control of the extremist group since May 2014.

"We know that the Iraqis have attempted on several occasions to open up humanitarian corridors to allow some of those civilians to come out" of Fallujah, Army Col. Steve Warren said last Friday in a video briefing from Baghdad to the Pentagon.

"Those have met with generally not much success," he said. "ISIL has done things like set up snipers to cover down on those corridors, to kill people as they're trying to get out. So that has really discouraged their use," he said, using another acronym for ISIS.

United Nations officials in Iraq have reported on a growing humanitarian crisis in Fallujah, with residents cut off from access to food and medicine.

"The UN reporting that I've seen certainly indicates that there are growing problems, that food is becoming scarce and that, you know, people who want to leave can't," said Warren, the spokesman for Combined Joint Task Force-Operation Inherent Resolve. "It's a legitimate humanitarian crisis."

Warren said Iraqi forces have been working to seal off the city but has run up against ISIS resistance. He said an effort last week by the Iraqis to move closer to the city gained only 340 meters.

"This is a tough city," he said. This is a tough nut to crack."

Under questioning from the Daily Beast's Nancy Youseff on why Mosul had preference over Fallujah in the strategy, Warren said, "I am confident that the Iraqis are aware that they need to liberate Fallujah. Where it falls into the sequence -- Fallujah before Mosul, Fallujah after Mosul -- is unclear.

"From a military perspective, Fallujah doesn't have much impact on Mosul. So, you know, you don't need to liberate Fallujah in order to get to Mosul," he said. "Fallujah doesn't really have any tactical influence on Mosul. So then it becomes a political decision, right? This becomes a decision that, you know, is made at the political level. There is no military reason to liberate Fallujah now, to answer your question."

The politics of the Shia-dominated Baghdad government also appeared to work against focusing on Sunni Fallujah, despite concerns in the capital that the recent spate of suicide bombings in Baghdad was coming from Fallujah.

In a national address Saturday, Iraqi Prime Minister Haider al-Abadi said that a "climate of dispute" in his government had given ISIS the space to operate and send truck bombs into Baghdad. "The political conflict among politicians and their impact on the brave security forces permits acts of terrorism to occur," he said.

Despite the political turmoil in Baghdad, Brett McGurk, the Obama administration's special envoy to the coalition against ISIS, told a news conference in Jordan on Sunday that the push on Mosul was progressing as an increasingly hard-pressed ISIS lacked the funding to attract more foreign fighters.

"We are doing precision strikes in Mosul almost every day," McGurk said, noting that the U.S. was also countering ISIS on social media. "For every pro-Daesh Twitter handle, there are now six calling out its lies and countering its message," he said.

Defense Secretary Ashton Carter has also left Fallujah out of the overall strategy against ISIS that he has said repeatedly now has two main goals -- retaking Mosul and Raqqa, the self-proclaimed ISIS capital in northeastern Syria.

After meetings with Abadi in Baghdad last month, Carter said the additional 217 U.S. troops and the Apaches would "enable the Iraqi security forces, and not try to substitute for them" in the Mosul offensive.

Apaches have been in Iraq since ISIS invaded in 2014, but Abadi denied permission for the U.S. to use them in assisting Iraqi forces in retaking Ramadi earlier this year.

Carter said that Abadi had now agreed to having the Apaches support a drive on Mosul, since the attack helicopters "can respond so quickly and so dynamically to an evolving tactical situation."

In his briefing last Wednesday, Maj. Gen. Volesky, who also commands the 101st Airborne Division, was reluctant to respond to questions on whether the Apaches had already been used in combat. He couched his response in double negatives: "I didn't say we hadn't used Apaches, and I won't say when or if we have."

Warren said later that the Apaches had yet to be used in an offensive operation and had been limited to flying security for VIP visits.

-- Richard Sisk can be reached at Richard.Sisk@Military.com.