Wall Street Journal (website) now reporting further statements by Group of 7 and EU, as well as ICAO Council:
"On Thursday, foreign ministers of the Group of Seven industrialized nations and the EU’s foreign policy chief called the diversion 'a serious attack on the rules governing civil aviation' and called on the United Nations’ International Civil Aviation Organization to investigate the incident. The ICAO later said it would do so, and ICAO Council President Salvatore Sciacchitano said the event 'posed apparent and serious threats to the legal framework' governing commercial aviation."
The same article reported on a "private" letter from MOL to Belarus CAA, protesting Belarus actions and disputing its version(s) of the events and communications.
( While supporting, generally, an action by ICAO "to investigate the incident", this SLF/atty questions what process, and by or under what specific authorities, ICAO investigatory action would be conducted. Thus far, no announcement or statement about this by ICAO has been located.)