Haniyeh was a noncombatant and a political leader, living in a US-allied country with the blessing of the USA (and now the other political leaders have just moved to Turkey, a NATO member to boot). Being a noncombatant affiliated with a group that your country has deemed a terror organization does not, under international law, give you carte Blanche to assassinate them.

Citation needed?

Pretty sure that being in a terrorist group, means you are considered a terrorist by the law, combatant or not.

https://il.usembassy.gov/state-department-terrorist-designat...