Former ABC News producer Max Oseredchuk was killed in a Russian drone attack while serving in Ukraine's military.
The U.S. believes that Russia has been providing Iran the locations of American troops in the region, including aircraft and ships, sources say.
The U.S. has confirmed that at least one American citizen is among the dead, and that another is among the injured receiving medical treatment.
Among the most difficult points are the fate of Ukraine's partially occupied eastern Donbas region and the nature of post-war Western security guarantees for Ukraine.
Russian opposition leader Alexei Navalny was poisoned by the Kremlin with a rare and lethal toxin found in the skin of poison dart frogs, five European countries said.
Ukrainian skeleton athlete Vladyslav Heraskevych was not allowed to compete after refusing a last-minute plea from the International Olympic Committee.