Uuuuh... as far as I'm aware, Russia has already been using cluster munitions in Ukraine. They used cluster munitions in Chechnya and Syria as well - and lots of them.
The US used them extensively in Iraq and Afghanistan, too... but that's okay, because those people don't "look like us" (apparently).
It's kind of weird that people are only now making a big fuss about them.
I thought it was just another indication that Putin really has no fucking clue WHAT is going on. It wouldn't surprise me if he believed Ukrainians were fighting with sticks and stones before the West started helping them out, but then again he also probably considers even that to be a threat to his fragile ego.