Former Trump White House national security adviser John Bolton flagged what GOP nominee Donald Trump did “wrong” following his controversial visit to Arlington National Cemetery this week.

Bolton appeared on CNN where host Phil Mattingly described Trump as “close” to the families of service members killed in Kabul during the U.S. withdrawal from Afghanistan.

The former White House official commented that he was surprised the U.S. Army put out a statement after Trump’s Arlington visit that said a campaign staffer “abruptly pushed aside” a cemetery employee, noting it was an “unusual” move for the Army to say something.

“And to be clear, what Trump may have done at Arlington with the families, whatever he said to them, pictures that were taken. That’s not anything that’s wrong,” Bolton said.

“What was wrong was what he did after they left the cemetery,” he continued. “By taking the films and so on and turning them into a political advertisement, that is what’s forbidden and that’s what he did. And I think that’s why people are legitimately upset.”

Arlington, a national cemetery with over 400,000 people buried on its 639 acres, prohibits political campaign or election-related activity at the site — rules that officials said they warned the Trump campaign about.

The former president, in remarks on the Arlington episode Thursday, claimed he didn’t “need the publicity” and blamed “bad people” in Washington for the matter.

Mattingly later mentioned that Trump campaign adviser Chris LaCivita shared footage of Trump at the Tomb of the Unknown Soldier earlier this week. Mattingly said he was allowed to take the video but noted that LaCivita said when he shared it that he hoped it triggered “the hacks” with the secretary of the Army.

“I have tremendous respect for his service, but they’re aggressively attacking on this issue. And I guess I don’t really understand why,” said Mattingly, who noted that LaCivita is a U.S. Marine Corps veteran and a Purple Heart recipient.

Bolton, who said he wished the Army chief of staff had been the one to issue a statement on the visit, said the campaign thinks the situation will help it but that the Trump campaign proves a point in “using the whole thing for political purposes.”

“That’s expressly what Congress was trying to prevent. And, and in the regulations that make it clear that that’s not what Arlington National Cemetery is for,” Bolton said.

“I can’t predict what the political outcome will be but it’s — I just think it’s shameful behavior.”