"so-called" is a very reserved and polite form of expressing doubt and scepsis.

President Putin told pupils on Friday, at the start of the school year, that Russia's triumph in World War Two proved that their nation was invincible.

"I understood why we won the Great Patriotic War," he said in a lecture designed to strengthen patriotism in schools. "It is impossible to defeat this kind of nation with this kind of attitude. We were absolutely invincible. And we are the same now."

The Kremlin's so-called "important conversations" were introduced in schools after the Russian full-scale invasion began.