Israeli Govt & IDF response to Hamas' Actions in Israel on the 9th Oct '23

Israel retaliated to the incursions into it's territory by Hamas, and Hamas actions inside Israel on the 9th October '23.
Israel called for international condemnation of Hamas' actions but then proceeded to blitzkrieg Gaza and perpetrated on the Palestinians what they claim was perpetrated on them.
How can this be justified, when violence begets violence begets more violence?
How can they operate an apartheid state, expansionist program, hold Palestinians in am open air prison, deny them water, food, medicine, a vote, their dignity etc and expect sympathy from the international community.