Russian hackers forced several Ukrainian and Latvian television channels to unintentionally broadcast parts of the annual Victory Day military parade in Moscow's Red Square.
In Ukraine, media groups Starlight Media and Inter, public television, and the channels Dim and Apostrophe TV were affected by the cyberattack, Detector Media, a media site, reported on Thursday.
In Latvia, media regulator chief Ivars Abolins said web and TV operator Balticom's programme was affected.
Russia traditionally commemorates the Soviet Union's victory over Hitler's Germany in 1945 with a military parade. Thursday's was the third of its kind since the beginning of the war in Ukraine, launched by the Kremlin in 2022.
It has been 79 years since the former Soviet Union, together with the United States and other allied powers, defeated Nazi Germany. But Russian President Vladimir Putin increasingly uses the commemoration of World War II to present his Ukraine war as an alleged continuation of the fight against fascism.
Amid the war, Ukraine has banned the broadcasting of Russian programmes.
The first disruption of Ukrainian media began right at the start of the military parade, according to the Detector Media report. The Kiev authorities said they have launched an investigation.
Latvian authorities are also investigating after disruption to Balticom's broadcasting infrastructure. The hackers here targetted a foreign partner of the company which is responsible for the programme content that Balticom broadcasts.