Some GovCon industry watchers expect the ongoing partial government shutdown to cost the Pentagon up to billions of dollars, Defense News reported Sunday.

Marcus Weisgerber writes the estimate takes into consideration the total bill from previous shutdowns, the duration, whether furloughed workers will receive back pay and inefficiency costs that would result from backlogs.

“Nobody is tabulating it currently, I’m sure,” Gordon Adams of American University told Defense News.

“Historical experience suggests it’s about $2 billion to $4 billion to lock it up and about $2 billion to $4 billion to unlock (the entire government),” said Adams, a former White Hosue budget official.

“It won’t cost you billions of dollars in the first year; It’s billions of dollars over the life of these programs,”Todd Harrison of the Center for Strategic and Budgetary Assessments told Defense News.

“If this goes on for a month, two months, three months, then programs and projects are really going to hit a brick wall,” he added.