After weeks of debate and number-crunching, the Defense Department announced plans Tuesday to furlough about 680,000 of its civilian employees for 11 days through the end of this fiscal year, allowing only limited exceptions for the military to avoid or reduce the unpaid days off.

Defense Secretary Chuck Hagel, in a memo to the department, called the decision “an unpleasant set of choices” between furloughing workers or cutting training and flight operations.

And during a town hall meeting with about 6,400 department personnel in Northern Virginia, Hagel was direct: “I tried everything. We did everything we could not to get to this day this way. But that’s it. That’s where we are.”

Telling the workers, he was sorry, Hagel said that after repeatedly going over the number, officials could not responsibly cut any deeper into training and other programs that affect the military’s readiness for combat. He added, “We’ll continue to search for ways to do better, but right now I can’t run this institution into the ditch.”

Hagel said that the department will be evaluating the budget situation over time and will try to end the furloughs early if at all possible. But he and other officials also warned that while they will do all they can to avoid furloughs in the next fiscal year, they can’t promise it won’t happen.

The furlough notices are expected to begin going out May 28, and workers will have several days to respond or seek appeals. The unpaid days off would begin no sooner than July 8, according to the memo. Officials said the furloughs will save the department about $1.8 billion.

“I understand that the decision to impose furloughs imposes financial burdens on our valued employees, harms overall morale and corrodes the long-term ability of the department to carry out the national defense mission,” Hagel said in the memo. “I deeply regret this decision.”

J. David Cox Sr., national president of the American Federation of Government Employees, called the furloughs a slap in the face to civilians who live paycheck to paycheck. He said the department’s decision “to impose such enormous economic pain on its own workforce, while continuing to lavish billions in new and unnecessary spending on wealthy contractors, is utterly shameful.”

Congressionally mandated automatic budget cuts initially forced the Pentagon to warn that the bulk of its 800,000 civilians would be forced to take 22 unpaid days off — one in each of the last 22 weeks of the fiscal year, which ends on Sept. 30. When lawmakers approved a new spending bill at the end of March, they gave the Pentagon greater latitude to find savings, and the furlough days were cut to 14.

Under pressure from military leaders and members of Congress, the Pentagon will allow the Navy to avoid furloughs for tens of thousands of workers at shipyards. Civilians make up the bulk of the workforce at those facilities and are key to keeping production lines going and preventing major backlogs in the repairs of ships and combat vehicles.

Officials expect that civilian intelligence workers in the National Intelligence Program — largely the CIA — will be exempt from furloughs. But civilians funded in the Military Intelligence Program will be subject to the unpaid days off.

Other exempt workers include civilians in the war zone and in critical public safety jobs, as well as people whose jobs are not paid for through congressional funding. As an example, some employees may be contractors or people working in facilities that pay for operations out of their earnings — such as some jobs in recreation or foreign military sales.