WASHINGTON — Forty percent of Pentagon contracts were indefinite delivery, indefinite quantity contracts, which potentially limit competition, a government watchdog agency reports.

Of the contracts, three-quarters were made to a single contractor, rather than multiple contractors, according to a Government Accountability Office report published Friday. GAO relied on data from 2015 through 2017 for the report.

The nine IDIQ contracts that GAO reviewed included ordering provisions that contemplated competition among the contract holders for subsequent orders.

“However, nearly all of the contracts we reviewed contained provisions that, while not explicitly limiting competition, may have the potential, under certain circumstances, to reduce the number of contractors who are eligible to compete for the orders,” the report concludes.

The use of these provisions was generally aimed at providing the government with the best value or to serve other goals, like increasing federal contracting opportunities for small businesses.

The GAO report did not make any recommendations, and the Defense Department did not comment on it.

The report comes as Defense Department officials defend their decision to award a potentially multibillion-dollar cloud contract — Joint Enterprise Defense Infrastructure — to a single vendor. In this case, they pointed to the current state of the commercial marketplace, existing acquisition laws and battlefield requirements as critical components.

Also last month, the U.S. Air Force selected Lockheed Martin to design and prototype a new hypersonic cruise missile, as part of a broad Pentagon push to kick-start America’s hypersonic arsenal — a single IDIQ contract worth as much as $928 million.