The pitch invaders were the Russian punk group Pussy Riot who released a statement regarding the release of political prisoners amongst things. No doubt they'll be getting another harsh prison sentence for their actions.
I take my hat off to them. Definetely takes a lot of courage, knowing that the sentence will be harsh and most of the public against you.
The four Pussy Riot members who rushed the field during the 2018 World Cup final in Moscow earlier this month have been arrested again today, July 30—the same day they were set to be released from prison. According to a statement from Pussy Riot’s Nadya Tolokonnikova, they were charged with “the organization and holding of public events without prior written notice,” which results in up to 10 days of arrest. See posts made on Pussy Riot's Twitter account below.
On July 15, Veronika “Nika” Nikulshina, Olga Kuracheva, Olga Pakhtusova, and Petya Verzilov ran onto the pitch during the World Cup Final game while dressed in old-fashioned police uniforms—a statement against Russia’s political and prison systems. They were then taken to the local police station and sentenced to “15 days of administrative arrest” and were prohibited from attending sports events for three years.
Immediately following the field rush, Pussy Riot shared a list of demands to the Russian government. It included “allow for political competition in the country,” ending “illegal arrests at protests,” and freeing political prisoners.