The killing on Tuesday night of a senior Hamas leader marked the biggest hit to the group’s top leadership in years, taking out a key player who was responsible for aligning the Palestinian militant group with Iran and Iran’s proxy Hezbollah.

Saleh al-Arouri was killed in Beirut in a suspected Israeli strike, although Israel hasn’t officially claimed responsibility. The death of Arouri, a Hamas political leader known for his diplomatic abilities and who helped establish the organization’s military wing in the 1980s, represents a symbolic and operational blow to the Islamist, Palestinian nationalist group.