As a round of peace talks wrapped up earlier this year, Ukrainian negotiators received a surprise offer from the Russians.

The Ukrainians could fly to Moscow and continue the talks, the Russians suggested. The upside: a potential meeting with President Vladimir V. Putin. The downside: possible arrest, or worse.

For Kyrylo Budanov, the Ukrainian delegation’s leader at the talks last February in Geneva, the proposal presented a stark choice. He is wanted in Russia on terrorism charges leveled when he was Ukraine’s military spy chief. But he, more than other Ukrainian leaders, has talked openly of needing to do what it takes, however unexpected, to reach a negotiated peace.

“I’m ready for any step that will end the war” if the terms are acceptable to Ukraine, Mr. Budanov, the No. 2 official in the Ukrainian government, said in an interview last weekend in the capital, Kyiv.

In the end, the proposed trip to Moscow, which was described by Mr. Budanov and has not previously been reported, never came together, and negotiations soon stalled.

But the episode showed the multiple facets of a man who, analysts say, is seeking to cement a legacy as a soldier who fiercely fought the Russians but went on to take the lead in bringing the bloodshed to a close.

Russia and Ukraine are currently in an escalatory cycle in the war, in part to try to gain the upper hand in eventual settlement talks.

Yet even as the two sides bombard each other with drones and missiles, Mr. Budanov said in the roughly hourlong interview that talks mediated by the Trump administration were expected to resume by late September, days after Russia’s parliamentary election and weeks before U.S. midterm elections.

The process, he said, is expected to restart with a visit to Kyiv by Steve Witkoff, the administration’s peace envoy, and Jared Kushner, President Trump’s son-in-law. While Mr. Witkoff and Mr. Kushner have traveled to Moscow several times, they have not been to Kyiv, despite multiple official invitations.

Mr. Budanov, 40, serves as President Volodymyr Zelensky’s chief of staff and is a lieutenant general in the Ukrainian military. As he advocates negotiation, he has little left to prove as a soldier who fought the Russians.

During the long-simmering war in eastern Ukraine that began in 2014, Mr. Budanov led commando raids behind enemy lines, including one that killed the son of a Russian general in combat.

He served in a C.I.A.-trained unit in Ukraine’s defense intelligence agency whose head was assassinated in a Russian car bombing in Kyiv. In 2016, a machine gun bullet shattered Mr. Budanov’s elbow. He was treated at Walter Reed National Military Medical Center in Maryland for months, as his arm was rebuilt. After the 2022 all-out Russian invasion, he helped mastermind some of Ukraine’s most audacious counterattacks.

Mr. Budanov still wears a military-style buzz cut and is known for piercing stares with his dark eyes. In an office adorned with a Christian icon painted on the ceramic plate of an armored vest, he pulled back the curtain a bit on the art of negotiating with mortal enemies.

Don’t waste time trying to prove you’re right, he said.

“Of course, we cannot trust one another because we are at war,” Mr. Budanov said. “That is logical and understandable. At the same time, both sides understand they need to search for a solution. The war cannot be eternal.”

The Ukrainian government has been divided over peace talks. In an analysis, the Carnegie Russia Eurasia Center described Mr. Budanov as leading a faction that advocates a settlement rather than risking greater losses. Other Ukrainian leaders, the group said, argue against any major concession, saying it would demoralize the army and society.

The Ukrainian public, for its part, has been skeptical of American-led talks. Before negotiations froze, many viewed the Trump administration as pushing for Ukrainian capitulation to further Mr. Trump’s quest for a Nobel Peace Prize. They also saw Mr. Putin as having no intention of ending the war, no matter what was negotiated.

Still, Mr. Budanov said he believed in keeping conversations open even while fighting. “I am an officer of military intelligence,” he said. “My whole life, I am in dialogues and communications. For me, this is not difficult.”

Russia and Ukraine have been talking since the first day of the 2022 invasion, when an aide to Mr. Putin tried unsuccessfully in two phone calls to negotiate a swift surrender.

Both sides have missed chances. About a month into the war, Russia walked away from a more balanced deal, only to then suffer a series of battlefield setbacks. Moscow lost about 10 percent of Ukraine’s land, which it might have retained had it accepted the deal, though the exact proposed territorial division was never made public.

A year later, Ukraine, on a roll then and brimming with confidence, missed a possible window for negotiations urged by the United States. Kyiv went on to lose about 1.5 percent of its territory to Russian advances.

A new flurry of talks began shortly after Mr. Trump took office in January 2025. But days after the Geneva meeting in February, the United States and Israel attacked Iran, opening a war that has consumed the Trump administration ever since.

Behind the scenes, lower-level negotiations carried on, Mr. Budanov said.

He said he had frequently talked with Adm. Igor O. Kostyukov, the head of Russia’s military intelligence agency, the G.R.U. They first negotiated in 2022, with Turkish mediation, to open Black Sea shipping channels for grain, a key export for both warring countries.

“Over the years, we were able to accomplish a lot, including on questions of prisoners of war,” Mr. Budanov said.

He maintained this dialogue even as he inflicted heavy losses on Admiral Kostyukov. Mr. Budanov keeps a photograph in his reception area of Ukrainian special operators storming a G.R.U. redoubt in a cement factory in the town of Vovchansk in 2024. That action killed many of the admiral’s soldiers.

Mr. Budanov said he had also spoken regularly with Yevgeny Prigozhin, the gregarious and murderous founder of the Russian mercenary company Wagner. Those conversations, Mr. Budanov said, continued until shortly before Wagner staged a mutiny against the Kremlin in 2023. Mr. Prigozhin died a few weeks later when his private jet blew up in midair.

One of the main reasons Mr. Budanov took the job as chief of staff this past January, he said, was the opportunity to lead negotiations.

By that time, Mr. Witkoff and Russian and Ukrainian negotiators had whittled a 20-point peace plan to two key unresolved points: management of a Russian-occupied nuclear power plant and control of territory that Ukraine still holds in the eastern Donbas region. At issue were four partly ruined midsize cities and a swath of farmland.

In talks in Abu Dhabi, Mr. Budanov tried to set a new tone, he said.

He said he told the Russian delegation that it should set a goal, like designing compromises for postwar governance in the Donbas, and work toward it.

By February, he said, potential ideas included handing the area over to private military contractors, allowing Mr. Trump’s Board of Peace to rule it, or forming joint Ukrainian and Russian civilian administrations.

Mr. Budanov said he had advised Mr. Zelensky not to accept any Donbas compromise that would allow Russia to claim control by flying its flag. To cede the territory would hand Moscow a prize that its military had proved incapable of taking.

While negotiations may resume this month, Mr. Budanov said, conditions for a cease-fire are unlikely to come until spring. Russia is expected to attempt to break Ukraine in another strategic winter bombing campaign, the fourth of the war.

“Negotiations will sooner or later come to something,” he said. “You cannot fight your whole life.”