There was no mistake.  Mistakes happen when people answer questions without fully understanding the nuances of the question or blurt out an answer without fully thinking it through, including the consequences of the answer.
Sajjan did not make a mistake.  He worked from a written speech that was well vetted and stated the same claim twice.
That is a bald faced lie and completely unbecoming a former military officer and completely unacceptable as a cabinet minister.  He must go and keeping him in cabinet is proof that Trudeau accepts liars in one of the most critical cabinet positions.