The number of security contractors the military employs in Afghanistan is higher now than at any time since President Barack Obama declared an end to combat operations in the country in 2014, Defense Department documents show.

More than 5,800 privately employed security personnel are currently operating in Afghanistan under Pentagon contracts, according to the latest report released this month that the military headquarters overseeing Middle East wars compiles for Congress. The number of security contractors jumped by more than 1,000 in the three months since the last report – a spike of more than 20 percent and the biggest increase in two years.

More than 17,000 uniformed troops from NATO and partner countries are currently operating in Afghanistan in support of local forces, up from roughly 13,000 when President Donald Trump took office. Of those, roughly 8,500 are Americans. Another 5,500 U.S. troops remain in Afghanistan for the separate mission of hunting insurgent forces like the Islamic State group and elements of the Taliban.

The last time the number of private security contractors exceeded 5,000 was in April 2014 during the height of the Obama administration's effort to withdraw all U.S. troops from Afghanistan. When Trump entered the White House in January 2017, the number stood at just over 3,400.

The new data comes amid concerns that the administration could increasingly turn to private companies to carry out the war. Officials and analysts, meanwhile, are raising alarm that the U.S. government is concealing the situation on the ground.

"The main problem with contractors of all sorts is there's just not enough attention to what they're doing. That's not been reported out in a clear way to anybody's satisfaction for all these years," says Catherine Lutz, a professor at Brown University and a director of its Costs of War project, which documents the use of private contractors in U.S. conflicts. "The Pentagon should be telling us, the American public, who's funding this, what that means, why this is happening."

"The main problem with contractors of all sorts is there's just not enough attention to what they're doing."

U.S. military headquarters in Kabul did not immediately respond to a request for comment. A Pentagon spokeswoman declined to provide further detail on how the military uses its security contractors and what accounts for the sudden increase.

Of the 5,883 security contractors outlined in the latest reports from U.S. Central Command, 2,567 of them are armed private security contractors. The rest provide support functions, like driving vehicles or other logistics work related to security activities.

Security contractors – both armed and unarmed – are a subset of a larger group of contractors who perform a broad range of tasks, including translation, construction and information technology services. But at nearly 20 percent of that pool, they now represent a bigger portion of all contractors than at any time since 2013. The Costs of War project has documented that as many as 2,800 contractors have died in Afghanistan – a figure that often goes unmentioned in public remembrances of the 2,400 U.S. military deaths in that war.

The extent to which the U.S. needs more security contractors because of a deteriorating situation on the ground is unclear, largely because the Trump administration, like its predecessors, has opted to withhold pertinent information. Faced with reports of a rising death toll among Afghan soldiers and national police officers, the government in Kabul – with U.S. support – stopped releasing those figures two years ago.

Even those who monitor the security situation there closely cannot discuss it publicly. When asked, for example, about the death rate among Afghan soldiers, which open source reporting indicates has reached unsustainable levels of as many as 40 per day, a top official tasked with scrutinizing reconstruction efforts in Afghanistan said he could not answer.

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"A lot of the answers or information to answer that question is classified now," John Sopko, the congressionally appointed special inspector general for Afghanistan reconstruction, told a small group of reporters earlier this week. "What we are finding now is almost every indicia, metrics, however you want to phrase it, for success or failure is now classified or nonexistent."

When pressed about whether the situation appears to be improving or worsening, Sopko again refused to answer, but added, "Governments don't usually classify good news."

Contractors have provided critical support functions in U.S. conflicts going back to the Revolutionary War and regularly carry out benign tasks like meal service and maintaining infrastructure on military bases. They may also be called upon to train local troops or service military equipment like helicopters.

In other circumstances, like with the subsequently rebranded firm Blackwater in the early days of Iraq, they provide security for high-profile officials or for U.S. bases and convoys. Prohibitions on their engaging in direct combat become murky when they operate in conflict zones where enemies move freely among the local populace. Blackwater, in particular, generated heated controversy for its heavy-handed battlefield tactics with seemingly little oversight.

And American leaders have relied on private security contractors to purposefully mask distasteful aspects of war. The Obama administration reportedly replaced troops that came home with private contractors, allowing it to maintain pressure on enduring enemies while publicly claiming the war was waning.

Lutz draws particular attention to Blackwater's founder Erik Prince, who has developed close ties with the Trump administration and who has advocated for Trump to turn over responsibility for the war in Afghanistan to private companies, akin to the British East India Company that governed colonial commerce in South Asia and whose use of private armies to maintain stability grew increasingly forceful. Prince's suggestion wrought widespread criticism .

In response to queries about the spike in the number of security contractors, Pentagon spokeswoman Heather Babb said in an emailed statement that military leaders in Afghanistan "continue to assess and right-size contracted support to provide executable options in pursuit of established strategic goals." She added that these leaders regularly conduct reviews of existing contracts "to identify requirements for reduction, consolidation, elimination, or transition to the Government of the Islamic Republic of Afghanistan."