U.S. Attorney General Merrick Garland is making an unannounced visit to Ukraine on Tuesday to help bolster an investigation into alleged war crimes during the Russian invasion, the Justice Department said.

Garland is meeting with Ukrainian Prosecutor General Iryna Venediktova “to discuss U.S. and international efforts to help Ukraine identify, apprehend, and prosecute those individuals involved in war crimes and other atrocities in Ukraine,” a Justice Department spokesperson told multiple media outlets.

The stop was part of Garland’s previously scheduled trip to Paris and Warsaw, Poland. The attorney general reportedly landed in Poland before heading to Krakovets, Ukraine — near the Polish border — for his meeting with Venediktova.

In a video posted to Twitter by Justice Department spokesman Anthony Coley, Garland tells Venediktova in front of reporters that he is in Ukraine “to express the unwavering support of the United States for the people of Ukraine in the midst of an unprovoked and an unjust Russian invasion.

"The United States is sending an unmistakable message,” he added. “There is no place to hide. We and our partners will pursue every avenue available to make sure that those who are responsible for these atrocities are held accountable.”

Venediktova thanked Garland for the United States’ support for Ukraine.

Garland and Venediktova, Ukraine’s top law enforcement official, last met virtually in May. 

U.S. prosecutors have been working with their Ukrainian and European efforts since at least April to help collect evidence of Russian war crimes. 

"This department has a long history of helping to hold accountable those who perpetrate war crimes," Garland said in April.

The attorney general is the latest U.S. official to visit Ukraine during the nearly four-month-old war. Others have included Defense Secretary Lloyd Austin, Secretary of State Antony Blinken and several members of Congress.

President Joe Biden visited Poland near the Ukrainian border in March, but did not enter the war-torn country.