U.S. cluster munitions have arrived in Ukraine, according to Joint Staff Director for Operations Lt. Gen. Douglas Sims.

Sims said that in contrast to Russia, Ukraine is aware of the possible danger to civilians, and does not intend to use them near population centers.

"I don't think that Ukrainians have any interest in using the cluster munitions anywhere near the civilian population, unlike the Russians," Sims told reporters.

-ABC News' Matt Seyler

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

U.S. National Security Council spokesman John Kirby said Thursday that "it remains to be seen" whether Russia has recovered from last month's brief but chaotic mutiny and if it will have any notable effect on the fighting in Ukraine.

"We don't exactly know what transpired every minute of that event and we don't really know what kind of impact it's going to have on the war in Ukraine," Kirby told ABC News' George Stephanopoulos during an interview on "Good Morning America."

"As we speak, there hasn't really been that much of an effect on the fighting in Ukraine," he added. "The Russians are dug in. The Ukrainians are trying to claw back territory. We're still trying to help them win."

Ukrainian forces are in the midst of a counteroffensive, "all the way from the Donbas area down toward Zaporizhia to the south," according to Kirby.

"They're making halting progress, not as fast [or] as far as they'd like to go, but we're going to do everything we can to give them the tools and capabilities to succeed," he said. "It could be weeks, it could be months of hard fighting here as they try to claim back the rest of their country."

Russian Foreign Intelligence Director Sergey Naryshkin claims he had a phone conversation with CIA Director William Burns in late June, according to the Russian state media outlet TASS.

"The bulk of the conversation was focused on discussing Ukraine and events around it. We gave some thought to and deliberated on what should be done about Ukraine," Naryshkin claimed to the outlet.

The CIA declined to comment about the alleged call.

The alleged conversation lasted "about an hour," according to Naryshkin.

The Russian intel chief noted that arranging an in-person meeting between him and the CIA leader remained a possibility.

-ABC News' Anastasia Bagaeva

Ukrainian Armed Forces have yet to reach their "full potential," but two top generals exclusively told ABC News the counteroffensive is "going to plan" despite concerns from Western analysts that Ukraine is not making enough progress.

Gen. Oleksandr Tarnavskyi, who is leading the counteroffensive in the south, told ABC News' chief global affairs correspondent Martha Raddatz that the situation is "stable."

"The main thing is that we haven’t reached our full potential," Tarnavskiy said.

Ukrainian troops launched the counteroffensive a month ago, attacking on multiple axes on the southern frontline in Zaporizhzia using Western-supplied vehicles. Ukraine succeeded in piercing Russian lines at two points, liberating a string of villages, but has since been locked in ferocious fighting

Gen. Oleksandr Syrskyi, commander of the Ukrainian ground forces, told Raddatz that last month's failed rebellion by the Putin-backed PMC, the Wagner Group, wouldn't impact the fighting on the ground.

"It would be better for us if there were some negative consequences in Russia itself, but it doesn't matter for me," he said.

Asked if he was confident of retaking the key city of Bakhmut, Syrskyi said, "Yes, of course. I’m sure."

Both sides have suffered heavy casualties, according to Western officials, particularly in the south where Russia has so far conducted "relatively effective defensive operations" in the southeastern Zaporizhzhia province, the U.K. Ministry of Defense reported.

"The enemy is suffering eight times or even 10 times higher losses, especially with the number of killed troops," Syrksyi said.

-ABC News' Guy Davies and Meghan Mistry