Hamas’ brutal attacks in Israel on October 7 killed at least 1,400 people and the group took more than 200 hostages, according to Israeli authorities. In the wake of the assault, Israel launched an aerial bombardment of Gaza that Palestinian health officials say has killed more than 5,000 people. Israel also announced a “complete siege” on the enclave, withholding vital supplies of water, food and fuel.
Because it’s not collective punishment. Collective punishment is things like the Bombing of Dresden or the Battle of Britain where a military/air force explicitly target civilian infrastructure. Declining to supply your enemy isn’t a war crime.
Israel disengaged from the Gaza Strip in 2004/2005. They’ve been self governing since then. Had they (Israel) forced a regime change in the past they would have been criticized by the world for reneging on their commitment to a two state solution. It’s not a great situation, but polling suggests that Hamas is incredibly popular in both the Strip and the West Bank.