What We Know About the Assassination of Ismail Haniyeh

The assassination of Ismail Haniyeh, one of Hamas’s most senior leaders, in Iran’s capital threatens to ratchet up tensions in the Middle East and could further imperil any prospect of a breakthrough in the already stalled negotiations to stop the war in Gaza.

Mr. Haniyeh was killed while he was in Tehran with other senior members of Iran’s “axis of resistance” — which includes Hamas in Gaza, Hezbollah in Lebanon and the Houthis in Yemen — to attend the inauguration of Iran’s newly elected president.

Hamas and Iranian state media on Wednesday blamed Israel for the death of Mr. Haniyeh, the militant group’s political leader, who was central to its high-stakes negotiations and diplomacy. Israel’s military has not commented on the assassination.

Here is what we know:

The killing comes at a tense moment.

Mr. Haniyeh was killed less than a day after Israel carried out a separate strike on a Hezbollah commander in a suburb of Beirut, in retaliation for a strike over the weekend in an Israeli-controlled town that killed 12 children and teenagers.

The assassination in Tehran leaves Israel facing potential responses from both Hamas and Hezbollah for attacks on their leaders, and from Iran for the killing within its borders.

Before the strikes, there were expectations that Israel and Hamas were nearing an agreement to pause the nearly 10-month-old war in Gaza that has left tens of thousands dead and prompted an ever-deepening humanitarian crisis in the enclave.