President Donald Trump on Monday suggested that NFL players who kneeled during the national anthem were disrespecting a soldier who was killed by friendly fire.

After spending the weekend attacking NFL players' right to protest the racist history of the national anthem, Trump appeared to still be upset about the subject on Monday.

But one retweet about Pat Tillman was exceptionally thoughtless.

NFLplayer PatTillman joined U.S. Army in 2002. He was killed in action 2004. He fought 4our country/freedom. #StandForOurAnthem #BoycottNFL pic.twitter.com/k1FXHRoozY

— Ⓙay (@jayMAGA45) September 24, 2017

In fact, football player-turned-soldier Pat Tillman was killed in action, but President George W. Bush's administration initially lied about the incident, blaming the Taliban. An investigation later found that U.S. soldiers had mistaken Tillman for the enemy.