Iran’s new supreme leader, Mojtaba Hosseini Khamenei, called for keeping the Strait of Hormuz closed amid continued U.S. and Israeli attacks on Iran.

In an audio message, he described the strikes as an “unjust aggression,” stressing that Iran will continue responding to military bases used in the attacks.

He also warned of the possibility of opening new fronts if the war continues, while Iranian officials cautioned that any attack on the country’s power grid could plunge the entire region into darkness.