Christie criticized the idea that the president could cozy up to Vladimir Putin, noting that all recent presidents have failed to engage Putin by not being tough enough. He then hit Trump for having said that Putin was "brilliant and a great leader." As the night has worn on, Christie continues to be really the only candidate who is bothering to attack the guy who is 40 or more points ahead of every other candidate in national GOP primary polls.

— Analysis by Geoffrey Skelley of 538

Ilia Calderón is asking about sending U.S. troops to Mexico. In a late August/early September survey by Morning Consult, 41 percent of Republicans said they thought that sending U.S. troops to fight cartels in Mexico would be “very effective” at limiting the supply of illegal drugs in the United States. Other strategies had more support among Republicans, such as sending more resources to the U.S.-Mexico border (54 percent), empowering U.S. law enforcement to combat opioids (45 percent), and punishing drug violators in the United States (43 percent).
—Analysis by 538

Haley going after Ramaswamy was a recurring theme in the first debate. They were the standout candidates in our polling last time and there was a lot of speculation about Ramaswamy moving up in the polls — perhaps even surpassing DeSantis. But since August, Ramaswamy has actually lost support, to the point where Haley passed him in our polling average today. It makes sense that they're trading blows again; this seems to be a successful strategy for Haley, and Ramaswamy can't help but take the bait.
-Analysis by G. Elliott Morris of 538

The candidates are discussing support for Ukraine. About half (49 percent) of Republicans and Republican-leaning independents say that vital U.S. interests are not really at stake in the war in Ukraine, according to an August Echelon Insights survey. Thirty-seven percent disagree, saying that if Russia wins, vital U.S. interests and values are threatened. Fourteen percent are unsure.
—Analysis by 538

Foreign policy isn’t quite dominating this debate, but U.S. policy towards China is a prominent theme, and Ramaswamy is bearing down a lot of attacks on that.

Ramaswamy and Haley had a heated moment on the debate stage over the issue of support for Ukraine – which Haley tied to China. When Ramaswamy argued against support for Ukraine, Haley jumped in, saying that a win for Russia is a win for China, and then accused Ramaswamy of liking China.

There was also the memorable TikTok exchange between the two. Haley sniped at Ramaswamy that "every time I hear you, I feel a little bit dumber for what you say” and that he can't be trusted as he justified his choice to join TikTok after being convinced by influencer and boxer Jake Paul to join despite previously calling it "digital fentanyl." TikTok was created by Chinese company ByteDance and lawmakers have scrutinized the app over security concerns. (Ads for TikTok are also airing on Fox Business Network during commercial breaks.)

Scott also accused Ramaswamy of being ‘bought’ by China. He was likely referencing Ramaswamy's company, Roivant Sciences, announcing 5-years ago that it was partnering with China state-owned investment company CITIC Group Corp

And Pence had a similar, pointed attack: “I'm glad Vivek pulled out of his business deal in 2018 in China -- that must have been about the time you decided to start voting in presidential elections."

It’s worth noting that Haley criticized Trump too on this front, in that case for not pursuing China aggressively enough on a host of issues: “This is where President Trump went wrong.”

– ABC News’ Kendall Ross, Libby Cathey, Soorin Kim, Abby Cruz, Nicholas Kerr, and Oren Oppenheim