WILMINGTON, Delaware/RAMALLAH: US President Joe Biden expressed hope Iran would stand down despite its threat to avenge the assassination of Hamas’ leader in Tehran, as fears mounted that Israel’s war against Palestinian militants in Gaza could escalate into a wider Middle East conflict. Regional tensions have soared following the assassination of Ismail Haniyeh, Hamas’ top leader, on Wednesday, a day after an Israeli strike in Beirut killed Fuad Shukr, a senior military commander from the Lebanese group Hezbollah, which like Hamas is backed by Iran.