The US military unleashed a new wave of strikes against Iran on Tuesday and revoked a license allowing the country to sell oil after three tankers were hit by projectiles in the Strait of Hormuz, putting pressure on an already fragile ceasefire.

After a day in which huge crowds mourned Iran’s martyred Supreme Leader Ayatollah Ali Khamenei in the holy city of Qom, US Central Command said it completed strikes that hit over 80 targets in an effort to impose what it called heavy costs.

The military command said it struck more than 60 small boats of the Islamic Revolutionary Guard Corps to degrade Iran’s ability to attack commercial shipping.

“The unwarranted aggression by Iranian forces is a clear and dangerous violation of the ceasefire and undermines freedom of navigation,” CENTCOM said in a statement.