The phrase "opens hostilities" means to initiate a conflict or war. Some synonyms for this phrase are "commence aggression," "start conflict," "begin combat," "launch an attack," "trigger a battle," "initiate warfare," and "provoke fighting." Additionally, other terms that can be used to describe starting a war include "declaring war," "launching an offensive," "going on the offensive," "unleashing violence," "starting a skirmish," or "instigating a confrontation." Regardless of the terminology used, initiating hostilities is never ideal and should always be avoided if possible. It can lead to widespread destruction, loss of life, and other negative consequences for all parties involved.