What to know about the escalating conflict and Israel-Hamas cease-fire talks after 2 assassinations

A pair of assassinations of anti-Israel militant leaders hours apart is threatening to set off a regional clash and upend already fragile talks aimed at ending the war in Gaza.

The deadly round of strikes, retaliation and negotiations escalated Wednesday when Hamas' political chief, Ismail Haniyeh, was killed, hours after he attended the inauguration of Iran's new president in Tehran. Israel has not claimed responsibility, but Iran threatened revenge against Israel.

It was the second assassination in less than a day to be blamed on Israel. On Tuesday, the Israeli military said it had killed Hezbollah commander Fouad Shukur in an airstrike in a Beirut suburb. The killing followed the rocket attack Saturday on the town of Majdal Shams that killed 12 young people in the Israeli-controlled Golan Heights. Iran-backed Hezbollah denied it was behind the Majdal Shams attack.

The U.N. Security Council was expected to hold an emergency meeting amid efforts to prevent Mideast tensions from boiling over.