A former U.S. Marine who was freed in a prisoner swap was injured while fighting in Ukraine, the State Department said.

Trevor Reed, the former U.S. Marine who was detained in Russia for nearly three years and later freed in a prisoner swap, was injured while fighting in Ukraine, the State Department said on Tuesday.

Mr. Reed’s condition was not immediately clear. He is receiving medical care in Germany, said Vedant Patel, a State Department spokesman. The news of his injury was first reported by The Messenger.

Mr. Reed was visiting his Russian girlfriend in Moscow in August 2019 when he was arrested on what his family said were bogus charges of assaulting police officers. The United States considered him wrongfully detained, and after months of diplomatic negotiations and mounting public pressure on the Biden administration, Mr. Reed was freed in April 2022 as part of a prisoner swap for a Russian pilot imprisoned on cocaine trafficking charges in the United States.

Mr. Reed’s decision to return to the region and become a volunteer fighter for Ukraine created some “exasperation” within the Biden administration, an administration official who spoke on the condition of anonymity to discuss sensitive matters said on Tuesday. The United States has repeatedly warned American citizens not to travel to Ukraine or participate in the war, though untold numbers of them have done so anyway.

“I want to be explicitly clear about something: Mr. Reed was not engaged in any activities on behalf of the U.S. government,” Mr. Patel said at a news briefing, adding that the country was “not in a place to provide assistance” to evacuate Americans who traveled to Ukraine.

A U.S. Defense Department official, who spoke on the condition of anonymity to discuss a sensitive issue, said on Tuesday that the United States was working with its partners and allies to address Mr. Reed’s situation, and the White House press secretary, Karine Jean-Pierre, told reporters that President Biden had been briefed on the matter. But Mr. Reed, now a private citizen, was transported to Germany through the help of an N.G.O. and not through U.S. government efforts, Mr. Patel said. Citing privacy reasons, he declined to specify whether Mr. Reed was being treated at a military or civilian hospital.

Mr. Reed’s release last year had renewed hopes for other Americans wrongfully detained in Russia, including the W.N.B.A. star Brittney Griner, who was freed in December through a separate prisoner swap. Two other Americans who are considered wrongfully detained remain: Paul Whelan, also a former U.S. Marine, and Evan Gershkovich, a Wall Street Journal reporter.

Asked about concerns that Mr. Reed’s decision to fight in Ukraine could jeopardize negotiations to secure the freedom of Mr. Whelan and Mr. Gershkovich, Mr. Patel said the United States would “continue to engage directly with the Russian Federation.”