Dakota Meyer, a Medal of Honor recipient and the son-in-law of 2008 Republican vice presidential candidate Sarah Palin, chided Donald Trump on Twitter Tuesday evening for not acting worthy of the Oval Office.

"If @realDonaldTrump wants to be the Commander in Chief, he needs to act like one. And that can't start until he apologizes to the Khans," wrote Meyer, a Marine Corps veteran.

Last week during a speech at the Democratic National Convention, Khizr Khan, whose son U.S. Army Captain Humayun Khan was killed in the Iraq War in 2004, pulled out a copy of the U.S. Constitution and asked Trump if he had ever read it, then said, "You have sacrificed nothing and no one."

The GOP nominee and Khan have sparred back and forth since then. Meyer says Trump, who his mother-in-law has endorsed for president, must apologize to move forward.

Palin has not weighed in on the incident, but Democratic nominee Hillary Clinton retweeted Meyer's message.