Haley, as a former ambassador, made an impassioned case for the U.S. continuing military and financial aid to Ukraine amid Russia's invasion.

"When you look at the situation, you have a pro-American country that was invaded by a thug," she said. "You want to talk about what has been given to Ukraine, less than 3.5% of our defense budget has been given to Ukraine. If you look at the percentage per GDP, 11 of the European countries have given more than the U.S."

She was interrupted by Ramaswamy, who is opposed to further assistance, and the two had a fiery back-and-forth.

Haley told the political newcomer: "You have no foreign policy experience and it shows."

On Ramaswamy's approach to Putin, Haley said: "This guy is a murderer and you are choosing a murderer."

-ABC News' Alexandra Hutzler

Scott just took a question about national security and turned it into one about immigration, saying our Southern border is the greatest national security threat. Ramaswamy did something similar earlier. If you look at the polling, it’s easy to see why: According to our FiveThirtyEight/Washington Post/Ipsos poll, 36 percent of Republicans identified “controlling immigration” as one of their top issues in the primary — second only to inflation and rising prices.
-Analysis by Nathaniel Rakich of FiveThirtyEight

Ramaswamy came out hitting the other candidates, saying he's the only one who hasn't been bought and sold. When it came to his comments on Ukraine, though, Pence and Haley are hitting back. "You have no foreign policy experience and it shows," Haley said. As Jacob said, his quick rise is drawing attacks, especially on his lack of political experience.
-Analysis by Monica Potts of FiveThirtyEight

Haley tried to go after DeSantis as he was answering a question on Ukraine but it didn't generate the same back-and-forth as with Ramaswamy, and the moderators quickly moved on to another matter. Clearly Ramaswamy -- his lack of political experience and rapid rise in the polls -- has gotten under the skin of the other candidates on the stage and they're going out of their way to take him down a peg even if it means forgoing opportunities against the ostensible polling leader.
-Analysis by Jacob Rubashkin, Inside Elections

Perhaps unsurprisingly, the pugnacious Christie repeatedly mixed it up with other candidates tonight. He was critical of Trump, calling the front-runner's behavior "unbecoming" and making him unfit to be president. Christie has a track record of strong debates, having shown in 2016 how he can throw a verbal punch, including his famous takedown of Marco Rubio just ahead of the New Hampshire primary that year. But Christie's criticism of Trump and his high unfavorable ratings among Republicans make his performance unlikely to cause a Christie boomlet in this race.

For Scott, tonight was an opportunity to capitalize on his potential as a candidate who is well-liked by Republicans familiar with him but who is not that well-known. And he largely tried to stay above the fray on most issues, which in theory made sense if he wanted to look like a consensus-style candidate who most Republicans could like. However, that also led to him getting less airtime, as the candidates who engaged each other and freely interrupted were more likely to be on camera. This debate doesn't hurt Scott, but I'm skeptical it helped him much.

-Analysis by Geoffrey Skelley of FiveThirtyEight