The leader of the Iranian-backed Lebanese terrorist group Hezbollah threatened Friday to exact revenge on the U.S. for supporting Israel in its campaign to root out Hamas.

Hezbollah Secretary-General Hassan Nasrallah said in a televised speech: “Let me be clear, the United States is just as responsible…Americans have to pay, they have to pay for Israel’s slaughter.”

A few days after Hamas invaded Israel, perpetrating the most brutal massacre against Jews since the Holocaust, Hezbollah terrorists clashed with Israel Defense Forces along the Lebanon border, opening a second front in the conflict.

If Israel’s military attacks Lebanon, where Hezbollah is operating, it will “pay dearly,” Nasrallah vowed.

Nasrallah applauded the hostile forces in the growing Middle Eastern coalition involved in the fight against Israel, which he described as a righteous “holy war.”

“We must salute the … strong and brave Iraqi and Yemeni hands who are now involved in this holy war,” he added.

The U.S. has so far deployed two aircraft carriers to the region, as well as military resources and aid, to deter Israel’s enemies from expanding the conflict. Since the early aftermath of the Hamas attacks, the U.S. military has also flown unarmed MQ-9 Reaper drones over Gaza to help Israel apprehend and rescue hostages being held by Hamas.

“Your Navy ships in the Mediterranean don’t scare us and they never did,” Nasrallah said Friday in a rebuke to the U.S.