See video of Sen. Dan Coats' oops

The people in the hearing room looked familiar to Sen. Dan Coats, as he launched into a question about the Defense Department's budget.

Only problem: The Indiana Republican wasn't where he was supposed to be and the witnesses arrayed before him weren't the Pentagon staffers he wanted to address about defense appropriations.

The Washington Postreports Coats, a former U.S. ambassador to Germany, had thanked the witness for responding to his query about the Indiana National Guard and was about to ask a question when a staffer handed him a piece of paper. Coats read it and said aloud: "I just got a note saying I'm at the wrong hearing."

David Cohen, a Treasury Department undersecretary, responded: "Well, that would explain why I didn't know anything about this letter."

Coats, who first served in the U.S. Senate from 1989 to 1999 before coming back in 2011, is quoted as saying in The Post report that such a mix-up had never happened to him before. He eventually got to the defense hearing.

Later, Coats poked a little fun at the situation, lightheartedly blaming the situation on Russia, which recently banned him from the country.

"I think the Russians have been messing with my schedule," he tweeted.