Maryland officials are warning drivers to expect traffic back-ups along Rockville Pike in Bethesda Tuesday afternoon.

Roads near the Walter Reed National Military Medical Center will be closed from 3:30 to 5:30 p.m. and that "could have a significant impact to local traffic," Montgomery County official Phil Alperson warned in an email.

Alperson said he did not know the reason for the closures.

"Everybody always assumes it's a presidential check-up, but I don't know," he said. "It could be anything."