Former Russian TV journalist Marina Ovsyannikova has been placed under house arrest for two months.
It is part of a criminal case where she is charged with spreading fake news about Russia's armed forces, Interfax news agency quoted a Moscow court as saying.
Ovsyannikova has already been fined twice in separate cases for protesting against the war in Ukraine, including by interrupting a live national news bulletin in March, shouting "Stop the war!" and holding up a placard telling viewers not to believe state propaganda.
In the latest case, she faces up to 10 years in prison if found guilty of distributing information about the Russian army that differs from government accounts.
It relates to a protest in July when she stood on a river embankment opposite the Kremlin and held up a poster calling President Vladimir Putin a murderer and his soldiers fascists.
"How many more children must die before you will stop?" The poster read.
Russia passed a new law against discrediting the armed forces on 4 March, eight days after invading Ukraine.
Interfax said Moscow's Basmanny district court had placed Ovsyannikova under house arrest until 9 October.
Officials at the court could not be reached for comment.
