Iran on Thursday announced alternative routes for vessels transiting the Strait of Hormuz, citing the potential presence of sea mines in the main shipping lanes. The move follows Tehran’s agreement to temporarily reopen the strategic waterway, which handles roughly one-fifth of the world’s oil shipments, as part of a two-week truce.

“All ships intending to transit the Strait of Hormuz are hereby notified that, in order to comply with maritime safety principles and to avoid possible collisions with sea mines, they should follow the designated alternative routes,” the Islamic Revolutionary Guard Corps said in a statement reported by local media. The statement included instructions for an alternative entry and exit route through the strait.

The two-week ceasefire between the United States and Iran was agreed overnight from Tuesday to Wednesday, just hours before a US ultimatum issued by President Donald Trump threatened military action if Tehran did not reach an agreement to reopen the strait.

Iran had effectively blocked the critical shipping corridor since early March, causing a surge in global energy prices and raising concerns over the security of international oil supplies.