Smoke rises from buildings as the sun sets in Beirut, Lebanon.
Smoke rises from the site of an Israeli airstrike in Beirut's southern suburbs on September 28.
  • 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.