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.

He said unstable young people were creating "fake heroes for themselves" and "reaching out for a surrogate for heroism" in the absence of the real thing.

"We're not creating healthy (internet) content for young people... which leads to tragedies of this kind," he said.

"But there is a place for real heroism in today's life," he said.