More than 700,000 applicants are awaiting security clearances, as the Office of Personnel Management struggles to clear the backlog.

“As of March, the process for a top secret security clearance took more than 450 days to conclude, a federal official reported in May, more than a half-year longer than it took in April 2016,” said the Washington Post.

OPM reported last year’s backlog at 570,000. The 700,000 figure for this year is an estimate from the Aerospace Industry Association, which wants clearances for aerospace workers.

But official figures are scarce, given that OPM has stopped disclosing the number of applicants waiting approval. “The decision to halt reporting comes as George Nesterczuk, the man President Trump nominated to lead the effort withdrew his name from consideration, leaving OPM without a permanent director,” the Post noted.

“This is a giant, giant problem,” Andrew Hunter, a military procurement expert with the Center for Strategic and International Studies, told the Post. “I’m told there are billions of dollars being spent for people who are on payrolls but they’re not able to do the work because they’re waiting for a clearance.”

Other experts blame the problem on the notorious 2015 hack of OPM records for millions of federal employees. “This really all started with the OPM breach,” former Department of Defense official Bill Greenwalt told the Post. “I think it’s gotten so bad that they stopped publishing it … there’s no sign of this backlog doing anything but growing.”