The U.S. attorney general meets with Zelensky during a surprise visit to Ukraine.

Attorney General Merrick B. Garland made an unannounced visit to Ukraine on Friday to reaffirm America’s commitment to help hold Russia responsible for war crimes, a Justice Department spokeswoman said.

Mr. Garland held several meetings with President Volodymyr Zelensky and foreign law enforcement officials in Lviv, while attending the United for Justice Conference, the department said in an email.

During the conference, Mr. Garland “reaffirmed our determination to hold Russia accountable for crimes committed in its unjust and unprovoked invasion against its sovereign neighbor,” the email said.

Mr. Zelensky, in his nightly address, said the thrust of the conference was to hold Russia’s leadership to account for atrocities committed by its army, a position he has hammered home repeatedly over the last year of war. “The main issue of all these meetings and the Lviv conference is accountability,” he said.

Mr. Garland’s visit, which was not public in advance for security concerns, comes on the heels of President Biden’s trip to Kyiv last month — and two days after Mr. Garland told members of the Senate Judiciary Committee that he was determined to hold Russians accountable for war crimes they are committing in Ukraine.

Mr. Garland, a former federal judge whose family escaped the Holocaust in Eastern Europe, singled out Yevgeny Prigozhin, the leader of the Moscow-allied Wagner paramilitary group.

“Mr. Prigozhin, who runs this thing, is in my view a war criminal — and maybe that’s an inappropriate for me to say with as a judge before getting all the evidence,” Mr. Garland told the committee.

Mr. Garland added that he believes the group “is responsible for the attacks on Ukrainians in the Donbas” and accused them of using prisoners from Russia “as cannon fodder” in Ukraine.

Last June, Mr. Garland made another surprise trip to Ukraine, where he met for an hour with Ukraine’s prosecutor general at the time, Iryna Venediktova, in the village of Krakovets, about a mile from the border with Poland, to discuss the technical, forensic and legal support that the United States could provide, department officials said.

He used the visit to announce the appointment of Eli Rosenbaum, a veteran prosecutor known for investigating former Nazis, to lead American efforts in tracking Russian war criminals.

The department is currently assisting Ukrainian prosecutors and its national police force with retrieving, storing and analyzing massive amounts of evidence being collected in connections with potential Russian abuses and atrocities.

In September, Mr. Garland met with Andriy Kostin, Ukraine’s current prosecutor general, in Washington to discuss those efforts and to sign a memorandum of understanding to increase coordination between their two agencies. They met again in Lviv, Ukraine, on Friday.