The U.S. military announced it will begin a blockade of all Iranian ports and coastal areas on Monday at 10 a.m., tempering President Donald Trump‘s earlier vow to entirely block the strategic Strait of Hormuz, as early reports indicated that ships had stopped crossing the waterway.

The move has set the stage for a showdown as Iran responded with threats on ports in the Persian Gulf and the Gulf of Oman.

“Security in the Persian Gulf and the Sea of Oman is either for everyone or for NO ONE,” according to the Islamic Republic of Iran Broadcasting, IRIB. “NO PORT in the region will be safe,” the Iranian military said.

Ceasefire talks between the U.S. and Iran ended in the early hours of Sunday without an agreement, raising questions about what happens when the current two-week truce expires on April 22.

Meanwhile, France and the U.K. announced they will organize a conference with partners ready to contribute to a peaceful multinational mission to help restore navigation in the Strait of Hormuz, President Emmanuel Macron said.

In a post on X, Macron stressed “the need to restore free and unimpeded navigation through the Strait of Hormuz as quickly as possible.” He called for a “peaceful multinational mission,” adding: “This strictly defensive mission, separate from the warring parties to the conflict, is intended to be deployed as soon as circumstances permit.”

France and the U.K. have in recent years been working to set up an operation that would allow ships to cross the Strait of Hormuz once the fighting ends.

An analyst has warned that the U.S. blockade of Iranian ports could prompt the Iranian-backed Houthi rebels in Yemen to disrupt transit through Bab el-Mandeb Strait.

“If the U.S. moves to impose a blockade on Iranian ports and Iran starts feeling the pain, the Houthis are very likely to escalate in the Bab el-Mandeb,” said Ahmed Nagi, a senior analyst for Yemen at the International Crisis Group think-tank.

The closure of Bab el-Mandeb would add “another layer” of pressure on the global shipping industry, he said.

Also on Monday, a labor union said that thousands of crew members stuck on vessels in and around the Strait of Hormuz are running short on basics and growing increasingly desperate.

Milind Kandalgaonkar, general secretary of the National Union of Seafarers of India, said that nearly 20,000 Indian crew members were stranded in the region.

“Many of these seafarers are reportedly facing acute shortages of food, potable water, and essential medical supplies,” he wrote in a letter to India’s national shipping board. He urged authorities to ensure supplies can reach the vessels, protect seafarers’ welfare, and prepare evacuation plans if needed.

Tanker owners say the ceasefire has done little to ease conditions for mariners in the strait, where crews report dwindling food and fresh water.

(AP)