In May 2019, during CyCon, the Estonian president described the Estonian view on cyber collective countermeasures. Since then, reflecting their unsettled status in customary international law, collective countermeasures have been a subject of increasing discussion. Support for collective countermeasures, particularly in the cyber domain, may be justified in the light of their increasing use during the last twenty years, stemming, among other things, from States’ reactions to Russian aggression in Ukraine.