The leader of the Lebanese militia group Hezbollah is calling the U.S. decision to designate Iran's Revolutionary Guard as a foreign terrorist organization "stupidity," and warns that the group and its allies may respond to any further escalation.

Hassan Nasrallah said Wednesday that the Trump administration's decision stems from the "failure" of its policies in the region.

The Guard is the main backer for Hezbollah, which plays an influential role in the Lebanese government and is already designated a foreign terrorist organization by the U.S.

Nasrallah said that although his group and Iran are sanctioned, that "does not mean we have no power cards."

Designating the Guard as a terrorist organization could also significantly complicate U.S. military and diplomatic work, notably in Iraq and Lebanon.