- Israel's assassination of Hezbollah leader Hassan Nasrallah was a major escalation.
- Nasrallah was one of Iran's most important allies.
- Iran's response could de-escalate the conflict or spark a wider war involving major global powers.
Israel's assassination of Hassan Nasrallah, the head of Hezbollah for over 30 years, is a major escalation in the Middle East conflict.
De-escalation is now up to Iran.