"Who knows what was in my head," he said in an interview with NBC's Chuck Todd on "Meet the Press" Sunday.
Todd played a clip of that interview, during which Stern asked Trump if he was for invading Iraq.
"Yeah, I guess so. You know, I wish the first time it was done correctly," Trump said then.
Then, Todd pressed Trump on what he meant when he'd said he wished "the first time it was done correctly."
"Well, what I mean by that is it almost shouldn't have been done. And you know, I really don't even know what it means, because that was a long time ago, and who knows what was in my head," he said. "I think that it wasn't done correctly. In retrospect, it shouldn't have been done at all."
Trump continued: "It was sort of, you know, it was just done. It was just, we dropped bombs. Now if you look back, actually, that was probably the correct way of doing it, not going in, and not upsetting, giving them a lesson or not."
"I mean, I think (George H.W. Bush) actually did a pretty good job of what he was doing," he said, giving Bush 41, who was president during the Persian Gulf War, credit for his handling of Iraq.
"He went in, he taught them a lesson," Trump said. "What happened is he was taunted. Because Saddam Hussein was saying, 'We drove back the Americans. The ugly Americans were driven back, the power of Iraq, the power.' Well, we weren't driven back. He just decided not, General (Norman) Schwarzkopf and others that maybe let's not go in."
Trump also dismissed the importance of his 2002 comments -- saying he'd made clear in the following months and years that he was opposed to George W. Bush's decision to go to war in Iraq.
"I was a businessman. I was a real estate man and a businessman. That was the first time I think that question was ever even asked of me. That was long before the war took place. That was, you know, many, many months before the war took place. And you could see by my answer, I wasn't exactly thrilled," Trump said.
He added: "The war in Iraq was a disaster. It was probably the worst thing. If you look at the Middle East now, all started because of that horrible decision to go into Iraq. And you know what we end up with? Nothing."