Gen. Mark Milley, the U.S. military's top general, told reporters Friday that it's likely too early to tell the impact of the Wagner Group mutiny on Russian President Vladimir Putin.

"We want to know the answer to that question," Milley said when asked at the National Press Club if Yevgeny Prigozhin's mutiny had left Putin weakened. "I don't think we have evidence, conclusive evidence, either way, yet too early to tell."

Milley acknowledged that Ukraine's counteroffensive is making steady progress, but moving slowly -- something he said was not surprising given how tough of a fight it is.

"At the end of the day, Ukrainian soldiers are assaulting through minefields and in the trenches, and this is literally a fight for their life. So yes, sure, it goes a little slow, but that is part of the nature of war," Milley said.

He also noted that the U.S. is considering sending cluster munitions to Ukraine, though no decision has been made.

-ABC News' Luis Martinez

Russian Gen. Sergei Surovikin has apparently been detained, according to a U.S. official. Other details about his status are unclear.

The development follows reports from a senior U.S. official on Wednesday that Surovikin had engaged in discussions with Wagner Group leader Yevgeny Prigozhin about his plans to mutiny.

Prigozhin is now exiled in Belarus.

-ABC News' Luis Martinez

Former Vice President Mike Pence made a surprise trip to Ukraine on Thursday, projecting solidarity against Russia in a way, so far, unmatched by his Republican competitors in the 2024 presidential campaign.

"As I made clear to President [Volodymyr] Zelenskyy today, when I return home, whatever the future holds for me and my family, we're gonna stand for freedom," Pence told reporters. "And I'll do my part to make sure that America continues to stand for the courageous fighters here in Ukraine that are fighting to reclaim their freedom."

Pence visited the sites of atrocities in the early phase of the war, in Irpin and Bucha, among other stops, before meeting with Zelenskyy inside the presidential palace in the capital of Kyiv.

Read more about the trip here.

-ABC News' Libby Cathey and Guy Davies

Ukraine recorded the "largest deterioration" of peace worldwide in the latest global peace report from the international think tank Institute for Economics & Peace.

"The war in Ukraine had a significant impact on global peacefulness, with Ukraine and Russia having the largest and fifth largest deteriorations in peacefulness respectively," the report stated.

Since last year's report, Ukraine fell 14 places to 157th among the 163 countries covered by the report. Due to the conflict, 65% of men in Ukraine ages 20-24 have fled the country or died, according to the report.

-ABC News' Emma Ogao

Coming off a "very productive summit" with NATO allies, President Joe Biden offered a forceful dismissal of Vladimir Putin’s efforts to capture Ukraine during a joint press conference in Helsinki with Finnish President Sauli Niinisto.

"There is no possibility of him winning the war in Ukraine. He's already lost that war," Biden said.

Biden has made similar statements before about Putin’s chances of success, though it’s particularly notable coming off of his meeting with Ukrainian President Volodymyr Zelenskyy and his top military officials Wednesday.

Biden wouldn’t give a timeline for how long he thinks the war can continue, but he ruled out a yearslong offense.

"I don't think the war could go on for years for two reasons. No. 1, I do not think that Russia could maintain the war forever -- No. 1 in terms of their resources and capacity. No. 2, I think that there is going to be a circumstance where eventually, President Putin is going to decide it’s not in the interest of Russia economically, politically or otherwise to continue this war," Biden said.

"But I can't predict exactly how that happens," he continued. "My hope is and my expectation is you’ll see that Ukraine makes significant progress on their offensive and that it generates a negotiated settlement somewhere along the line."

-ABC News' Molly Nagle and Cheyenne Haslett