Russian President Vladimir Putin on Thursday said the mass school shooting in Crimea a day before was the result of "globalisation" and the continuation of an American trend.
"It's a result of globalisation. On social media, on the internet, we see that there is a whole community that has been created. Everything started with the tragic events in schools in the US," he said at a forum in Sochi.
"We're not creating healthy (internet) content for young people, which leads to tragedies of this kind," he said.
An 18-year-old identified as Vladislav Roslyakov on Wednesday killed at least 20 students at a college in the Moscow-annexed peninsula before killing himself.
More than 40 others were injured in what local press dubbed "Russia's Columbine", a reference to a 1999 US high school massacre.
Authorities said they were working to establish the motive for the attack.
An ex-girlfriend told Russian state media Roslyakov had spoken to her about taking revenge for being bullied at the school.