The US is responding to the heightened tensions by moving more military assets into the region and working to assemble a coalition similar to the one that helped Israel defend against Iran's massive missile and drone attack in April.
The message was reportedly delivered by a top Kremlin ally during meetings with Iranian officials as the Islamic Republic considers its reaction to Ismail Haniyeh's death.
"While Iran has no interest in exacerbating regional tensions, we believe it is necessary to hold Israel accountable to prevent further instability," Iranian Foreign Ministry spokesman Nasser Kanani says.
"They'll just try to wear us out," unnamed Israeli official tells NBC News after the assassination of Hamas political leader Ismail Haniyeh in Tehran.
Ayman Safadi to meet Iranian counterpart in bid to ease tensions after assassination of Hamas chief Ismail Haniyeh.
The Iranian Revolutionary Guard claim that Ismail Haniyeh's assassination was carried out 'with the support of the criminal U.S. government.' Additionally, they promise revenge: 'The adventurous and terrorist Zionist regime will receive a decisive response to this crime.'
Saudi channel Al-Hadath reported that the state of alert is at its peak in Lebanon and Syria. American officials estimate that the upcoming attack on Israel may be more significant than the one in April.
Five separate sources informed Reuters that representatives from Yemen's Houthi rebels, Lebanon's Hezbollah, Palestinian Hamas, and Iraqi Shiite militias met with top Islamic Revolutionary Guard Corps officials in Tehran.
The assassination of the Hamas political bureau dominates headlines across Arab media.
The New York Times reports that Iran's Supreme Leader Ali Khamenei has ordered a direct attack on Israel, in retaliation for the assassination of Hamas leader Ismail Haniyeh in Tehran, attributed to Israel.
