Reuters reported on the 21st (local time) that Yemen's Iran-aligned Houthi rebels warned global shipping companies to stop using Saudi Arabian ports.
According to the report, the Humanitarian Operations Coordination Center (HOCC) under the Houthis said in an email sent the previous day to multiple global shipping firms, "We prohibit the loading and unloading of cargo for vessels at all ports of Saudi Arabia."
The Houthis continued, "Vessels in violation will be exposed to the risk of sanctions," warning that "they may become targets anywhere within the Yemeni military's operational radius." They added, "We strongly advise exercising utmost caution and making best efforts in all transactions."
The warning is interpreted to mean a blockade of the Red Sea route that Saudi Arabia uses as an oil transport corridor to bypass the Strait of Hormuz. Reuters said, "If the southern Red Sea is closed, Saudi Arabia will lose an alternative route to bypass the Strait of Hormuz."
Earlier, the Houthis declared a maritime blockade against Saudi Arabia, saying it was a retaliatory measure for Saudi Arabia's bombing on the 13th of Sana International Airport, which is controlled by the Houthis. Houthi Spokesperson Yahya Sarea said, "In accordance with the principle of 'an eye for an eye,' we declare a maritime blockade against Saudi Arabia, a criminal state, and this takes effect immediately."