The Pentagon spent up to $7 trillion on contractors who "took advantage of wartime conditions" in the wake of 9/11, a new study released on Monday suggests.

The figure represents as much as half of the Defense Department's $14 trillion expenditure since the war in Afghanistan began in 2001 and the War on Terror went global, according to Brown University's Costs of War Project.

Its research found that contractors used the military rush "to overcharge the government or engage in outright fraud" amid the Pentagon's demand for rapid assistance and "less rigorous oversight."

Up to one-third of the expenditures granted to contractors went to just five companies: Lockheed Martin, Boeing, General Dynamics, Raytheon, and Northrop Grumman. Lockheed Martin alone received $75 billion in fiscal year 2020, which is more than 150% of the State Department and US Agency for International Development's $44 billion budget for that year, the study said.

With the US completing its withdrawal from Afghanistan last month, and attempting to pivot its military posture away from the War on Terror, there is a new rationale already in place to continue the outsized spending.

- As the U.S. reduces the size of its military footprint in Iraq and Afghanistan, exaggerated estimates of the military challenges posed by China have become the new rationale of choice in arguments for keeping the Pentagon budget at historically high levels," the study said. "Military contractors will continue to profit from this inflated spending. -