"The bottom line is, Sen. Harris, when you were in a position to make a difference and an impact in these people's lives, you did not and worse. Yet in the case of those who were on death row, innocent people, you actually blocked evidence from being revealed that would have freed them until you were forced to do so," she said. "There's no excuse for that and the people who suffered under your reign as prosecutor, you owe them an apology."

But Gabbard's debate performance wasn't just marked by confrontation. She wielded her credentials as an Iraq war veteran to speak about foreign policy decisions in a personal manner, charging the US must "bring our troops home."

"For too long, we had leaders who have been arbitrating foreign policy from ivory towers in Washington without any idea about the cost and the consequence, the toll it takes on our service members, on their families," Gabbard said. "We have to do the right thing. End the wasteful regime change wars and bring our troops home."

Ending the American conflicts in Iraq and Afghanistan, she added, should not be about the setting of "arbitrary deadline." It's a question, Gabbard said, "about leadership."

"The leadership I will bring to do the right thing, to bring our troops home within the first year in office because they shouldn't have been there this long," she said.

Turning to Trump, Gabbard added: "We were all lied to (about Iraq). The problem is that this current President is continuing to betray us."

Wednesday's debate also saw Gabbard draw on her childhood in Hawaii to speak about climate change, arguing the issue is "personal" for her.

"First of all, this is personal," she said. "You can imagine, I grew up in Hawaii, which is the most remote island chain in the world. So for us growing up there, protecting our environment was not a political issue, it's a way of life. It's part of our culture. It's part of who we are."

In her closing remarks, Gabbard made a simple plea to voters.

"As president, I will end this insanity," she said. "It doesn't have to be this way."