Ethnic cleansing is a term that has been used frequently in the context of this conflict. It is not, however, recognized as an independent crime under international law. It may constitute an element of a crime falling under the ICC jurisdiction—and I would note Armenia has just signed on to the ICC—such as crimes against humanity or certain war crimes when the conditions for the commission of such crimes are met.
A legal determination of those things needs to be done by a competent international or national court or tribunal. In the absence of a viable route to determination by an international court or tribunal, an investigation by an independent and impartial investigative body, ideally established by the UN and its associated bodies and agencies, could form the basis of a potential recognition of these crimes.
There is no doubt that some horrific things happened, but for a determination at law, we would look to a legal process to make that determination.