"As a result of the violation of the ceasefire regime, the Strait of Hormuz will be closed from the evening of today [Saturday], until the US lifts the naval blockade," the IRGC Navy said, as quoted by Iran's state-run IRIB broadcaster.
The IRGC also warned of strikes on any vessels that attempt to approach the waterway, which will be considered as "cooperation with the enemy [the US]."
On April 13, the US Navy began blockading all maritime traffic entering and exiting Iranian ports on both sides of the Strait of Hormuz, which accounts for approximately 20% of the world's oil, petroleum products, and liquefied natural gas supplies. Washington maintains that non-Iranian vessels are free to transit the Strait of Hormuz as long as they do not pay Tehran a toll. Iranian authorities have not announced the imposition of a toll, but have discussed such plans.