"I saw today -- I left the room and I saw a commercial where it was really a nasty commercial, totally made up about me with vets. There is nobody that loves the vets more or respects the vets more," Trump said. "They're spending hundreds of millions of dollars on false commercials and it's a disgrace. So what we'll do -- I guess we'll sue them. Let's sue them. Right? Let's sue them."
Trump did not specify which ad he was referring to or which group ran the ad. His campaign did not respond to requests for details.
But the Clinton campaign launched an eviscerating ad last month entitled "Sacrifice" that featured veterans watching Trump make disparaging comments about veterans and the military, including his comment arguing that Sen. John McCain, who was tortured for several years as a prisoner of war in Vietnam, was "not a war hero."
"He's a war hero because he was captured. I like people that weren't captured, OK?" Trump said of McCain.
The ad, which followed Trump's repeated feud with the family of Khizr Khan, a Muslim US soldier who died in Iraq, also features Trump's comments in an interview about the feud.
"I think I made a lot of sacrifices, built great structures, I've had tremendous success," Trump said in the interview featured in the Clinton campaign ad, apparently comparing his sacrifices to those of US military veterans.
Trump made his latest gaffe
about military veterans when he suggested during an event Monday in Virginia that war veterans commit suicide as a result of PTSD because they "can't handle it" as opposed to those who are "strong."
"When you talk about the mental health problems, when people come back from war and combat and they see things that maybe a lot of folks in this room have seen many times over and you're strong and you can handle it but a lot of people can't handle it. They see horror stories, they see events you couldn't see in a movie, nobody would believe it," Trump said during a panel interview at the Retired American Warriors PAC in Herndon, Virginia.
The lawsuit Trump floated on Wednesday is not the first time Trump has threatened to file a lawsuit over the course of his presidential campaign.
Trump has repeatedly threatened to sue news outlets for running articles portraying Trump in a negative light -- regardless of how truthful the claims were.
The litigious New York billionaire also threatened in February to sue Ted Cruz to determine whether the Canadian-born Texas senator is a "natural born citizen."
And last year, Trump's attorneys sent a cease and desist letter to the Club for Growth after Trump threatened to sue over attack ads the conservative advocacy group was running against Trump during the Republican primaries.