Nearly a month after Defense Secretary Ash Carter announced plans to an expanded the U.S. military mission in Iraq, little additional U.S. combat power has reached the front lines outside Mosul where in the Iraqi army has been slow to reclaim ground from well entrenched fighting against Islamic State militants outside Mosul.

Those plans, In April Carter announced in April, authorized the deployment the authorization of several American key "enablers," for the Iraqi Army, including more than an 200-plus U.S. additional troops and the addition of combat advisers within the Iraqi army's combat down to the brigades and battalions. They also included an levels and also the offer of U.S. Army Apache attack helicopters to provide close air support for Iraqi ground forces.

However, Since then, however, the number of U.S. troops in Iraq has declined slightly since then. American and teams of U.S. military advisers are not yet working at the brigade or battalion levels, military officials say. And officials won't will not say whether any of the U.S. Army's AH-64 Apache helicopters in Iraq have been employed deployed for combat operations.  

The Sending additional U.S. combat power to Iraq was intended to boost the Iraqi army’s push toward the Islamic State stronghold of Mosul, the Islamic State's stronghold in Iraq. But the Iraqis' effort, officially launched in March, has advanced very slowly. So far, they've and seized only a few small villages near their Iraqi army base in Makhmur.  

One of the top U.S. commanders in Iraq said Wednesday that the use of additional U.S. forces and assets is largely driven by the Iraqis' needs of the Iraqi Army

"The Iraqis are leading this fight," Army Maj. Gen. Gary Volesky told reporters Wednesday

"The capabilities that we provide are really based on supporting the Iraqi Security Force plan," said Volesky, who is the head of Operation Inherent Resolve’s Combined Joint Forces Land Component Command. "Any of these capabilities that we bring in ... we work with the government of Iraq. We're going through the training and the advise-and-assist piece, to identify capability gaps they may have. And then we recommend a few that we could potentially provide," said Volesky, who is currently the head of Operation Inherent Resolve’s Combined Joint Forces Land Component Command."

On April 18, Carter said the White House had authorized an increase in the U.S military force level in Iraq by 217, raising the current troop cap above to more than 4,000. But since April 18, the number of deployed troops officially deployed to Iraq has dropped from 3,540 to 3,460 on Wednesday, a military official said.

A U.S. Marine, left, provides instruction to an Iraqi soldier, assigned to the 7th Iraqi Army Division, on UHF radio operations at Al Asad Air Base, Iraq, March 30, 2016. Communication training is one of the skills taught at Al Asad as part of the building partner capacity mission, which increases the military capabilities of Iraqi Security Forces to fight the Islamic State of Iraq and the Levant. By enabling ISF through advise and assist, and BPC missions, the Combined Joint Task Force – Operation Inherent Resolve’s multinational coalition is helping the Government of Iraq to set the conditions to defeat ISIL. (U.S. Army photo by Sgt. Joshua E. Powell/Released)
A U.S. Marine, left, provides instruction to an Iraqi soldier, assigned to the 7th Iraqi Army Division, on UHF radio operations at Al Asad Air Base, Iraq, March 30, 2016. Communication training is one of the skills taught at Al Asad as part of the building partner capacity mission, which increases the military capabilities of Iraqi Security Forces to fight the Islamic State of Iraq and the Levant. By enabling ISF through advise and assist, and BPC missions, the Combined Joint Task Force – Operation Inherent Resolve’s multinational coalition is helping the Government of Iraq to set the conditions to defeat ISIL. (U.S. Army photo by Sgt. Joshua E. Powell/Released)

A U.S. Marine, left, provides instruction to an Iraqi soldier on UHF radio operations at Al Asad Air Base on March 30.

Photo Credit: Sgt. Joshua E. Powell/Marine Corps

Having Carter said the White House authorized putting ground-level combat advisers embedded with the Iraqis at battalion and brigade . Sending those American troops out to brigade and battalion command posts would put them closer to the front-line fight, and streamline the flow of air strikes and other critical American combat support to Iraqi units fighting the Islamic State, also known as ISIS or ISIL. But military officials say the U.S. combat advisers remain at higher division and headquarters levels, where they've been for months. 

U.S. commanders are cautious about sending combat advisors to those lower-level commands in part because those locations are far more dangerous.

"How we advise and assist, again, is a very deliberate decision. And where we put those advisers, we make sure that we've mitigated the risk to the force. As I said, force protection is job one," Volesky said.

Volesky declined to say whether any Apaches have been deployed in support of Iraq forces.

Volesky declined to say whether he thought the Iraqis would invade Mosul this year. He said the Iraqis are struggling to find enough manpower.

"Some of the challenges they have, frankly, are force generation. … Generating a force to get through training, get ready to go up to Mosul, it requires them to move that piece out of another location that's been cleared. And so they want to make sure that they're doing that very deliberately," the general said.

During the past several weeks, the Iraqi's have seized "four or five villages" as they move from their large logistics hub of Makmour inside Kurdish-controlled territory to Qayyarah, an along the Tigris River.

The Baghdad government has been roiled by protests and political battles for the past several weeks.

Vice President Joe Biden visited Iraq on April 28 and urged Iraqi leaders to set aside their political differences and focus on defeating ISIS.