Haniyeh was largest obstacle to hostage deal on Hamas side
Both Iran and Hezbollah are expected to retaliate for the killings
Killings of Haniyeh and Shukr could increase threats to Israel and US forces
Haniyeh was in Iran for inauguration of newly elected President Pezeshkian
Haniyeh was targeted hours after assassination of Hezbollah's chief of staff in Beirut
Israel and US reject ICC’s jurisdiction to issue arrest warrants for Israeli leaders