The White House is actively considering a bold plan to turn over a big chunk of the U.S. war in Afghanistan to private contractors in an effort to turn the tide in a stalemated war, according to the former head of a security firm pushing the project.

Under the proposal, 5,500 private contractors, primarily former Special Operations troops, would advise Afghan combat forces. The plan also includes a 90-plane private air force that would provide air support in the nearly 16-year-old war against Taliban insurgents, Erik Prince, founder of the Blackwater security firm, told USA TODAY.

The unprecedented proposal comes as the U.S.-backed Afghan military faces a stalemate in the war and growing frustration by President Trump about the lack of progress in the war.

The U.S. military has 8,400 U.S. troops there to train and guide local forces. They do not have a direct combat role, and presumably would be replaced gradually by the contractors.

The plan remains under serious consideration within the White House despite misgivings by Trump's national security adviser, H.R. McMaster, an Army three-star general, and Defense Secretary Jim Mattis. Other White House officials, such as chief strategist Stephen Bannon, appear open to using private contractors.

“At what point do you say a conventional military approach in Afghanistan is not working,” said Prince, a former Navy SEAL. “Maybe we say that at 16 years.”

Blackwater, founded 1997, worked extensively in the wars in Iraq and Afghanistan. Prince sold the company in 2010.

The White House did not respond to requests for comment.

Prince said the plan will cost less than $10 billion a year, significantly lower than the more than $40 billion the Pentagon has budgeted this year.

The prospect of accomplishing more with less money could appeal to a career businessman like Trump.

Prince, who has met frequently with administration officials to discuss his plan, is the brother of Trump's education secretary, Betsy Devos.

Under his proposal, private advisers would work directly with Afghanistan combat battalions throughout the country, and the air force would be used for medical evacuation, fire support and ferrying troops.

Prince said the contractors would be “adjuncts” of the Afghan military and would wear that nation’s military uniforms. Pilots would only drop ordnance with Afghan government approval, he said.

Currently, troops from a U.S.-led coalition are stationed primarily at top level headquarters and are not embedded with conventional combat units in the field. Under the plan the contractors would be embedded with Afghanistan's more than 90 combat battalions throughout the country.

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The coalition sharply curtailed air support it provides Afghanistan forces by 2014, when government forces took over most war-fighting responsibilities, leaving major gaps in the Afghan military's ability to provide air support.

Secretary of State Rex Tillerson acknowledged this week that the White House is looking for a new strategy to bring America's longest war to an end.

“To just say we’re going to keep doing what we’ve been doing, the president is not willing to accept that, and so he is asking some tough questions,” Tillerson said Monday in Manila during an Asia trip.

U.S. troops invaded Afghanistan in October 2001 to oust a government run by Taliban extremists who provided safe haven to al-Qaeda terrorists responsible for the 9/11 attacks.

The top U.S. commander in Afghanistan, Gen. John Nicholson, has recommended that several thousand more troops be deployed to Afghanistan, primarily to bolster the advisory mission and help turn the tide against the Taliban.

Mattis has indicated he doesn’t want to make a decision on troop levels until an overall strategy has been approved. But the way forward is still under debate at the White House.

“The president doesn’t own the Afghan effort yet,” Prince said of a war that frustrated Presidents George W. Bush and Barack Obama. “He’s about to (with) whatever decision he makes next.”

Prince rejects criticism that he and others would profit from it. He said it would represent a cost savings for American taxpayers. “The idea of innovation and risk taking is certainly part of America,” he said.

Blackwater has attracted controversy under Prince's leadership. In 2007, four Blackwater security personnel were accused of killing 14 Iraqi civilians in Baghdad. Last week an appeals court overturned a murder conviction for one of the guards and ordered the other three to be re-sentenced.

Blackwater was renamed Xe Services two years after the incident that sparked international outrage. The privately owned company is now Academi.

Tens of thousands of contractors were used in the wars in Iraq and Afghanistan. Blackwater was hired to protect American diplomats in Iraq, while other contractors were used in support functions, such as providing food and supplies to U.S. troops. The U.S. military rarely deploys anywhere now without a contingent of contractors.

A close parallel to Prince's proposal in U.S. history may be the Flying Tigers, a group formed before the United States entered World War II. The Flying Tigers were formed covertly from the ranks of U.S. military pilots, who resigned from the service and were hired by a private contractor and sent to China to defend against Japanese aggression.