Russian authorities have also not provided the United States with any additional details on the whereabouts of two Americans captured in Ukraine, State Department spokesperson Ned Price said on Tuesday.
Price told reporters the US is pursuing every channel and every opportunity to learn more and support the families of Americans missing in Ukraine.
An unknown number of foreigners, including Americans, have flocked to Ukraine since Russia invaded in February, joining the Ukrainian armed forces.
Ukraine has established an international legion for volunteers with varying degrees of previous military training. With many sent to the frontlines, there’s been a steady trickle of reports of individuals killed, captured or missing.
The State Department on Tuesday confirmed that a second American had been killed, identifying the man as 52-year-old Stephen Zabielski, and again issuing the now almost daily plea for US citizens to keep away.
“We once again reiterate US citizens should not travel to Ukraine due to the active armed conflict and the singling out of US citizens in Ukraine by Russian government security officials,” a State Department spokesperson said.
“If you want to help the people of Ukraine, there’s a whole lot of other better options to do that than to go in and put yourself in harm’s way,” Kirby said.
The two captured Americans are both former servicemen and were taken prisoner in the east of Ukraine earlier this month.
Alexander Drueke and Andy Huynh, previously living in Alabama, have appeared in videos and pictures aired by Russian state media and social media, but President Joe Biden said last week he does not know exactly where they are being held.
The State Department says Russia is required to treat volunteers humanely as they would other prisoners of war in accordance with the Geneva Conventions, which prohibit execution and torture or other mistreatment of war detainees.
A 22-year-old former Marine, Willy Joseph Cancel, was confirmed as the first American killed fighting for Ukraine in late April.
A third missing American, identified as a former US Marines captain with 20 years experience, was last heard from in late April, CNN quoted his wife as saying.
Two British men and a Moroccan captured in fighting have been sentenced to death by the Russian proxy authorities in the so-called Donetsk People’s Republic, a Moscow-controlled swath of eastern Ukraine.