The government of a country makes explicit or implicit threats to another: "if you cross this line, we will inflict harm upon you." The threat fails; the government crosses the designated line. Has deterrence failed? Well, yes. Of course. By definition. It is, for example, unequivocally true that the United States did not deter Russia from invading Georgia in 2008, nor Ukraine in 2014, nor Ukraine (again) in 2022. Should you have any doubts...