MAR-A-LAGO, Florida - Former President Donald Trump has defended acquitted teenager Kyle Rittenhouse, 18, who has been prosecuted over the shooting deaths of two men, and the wounding of a third, in August last year in Wisconsin.

Mr Trump said the teenager should not have faced a trial.

"Really a nice young man. What he went through - he should've, that was prosecutorial misconduct," Mr. Trump said Tuesday.

"He should not have had to suffer through a trial for that. He was going to be dead. If he didn't pull that trigger, that guy that put the gun to his head, in one-quarter of a second, he was going to pull the trigger - Kyle would've been dead," the former president said in an interview with Fox News's Sean Hannity.

"Just left Mar-a-Lago a little while ago and he should never have been put through that. That was prosecutorial misconduct, and it's happening all over the United States right now with the Democrats."

Mr Trump said he had been visited by the teenager at Mar-a-lago and spent an hour with him and his mother.