The U.S. military said it would begin a blockade of all Iranian ports on April 13, after talks between the warring sides in Pakistan collapsed, and despite the Iranian military warning that it would treat any such action as an act of piracy.
Trump had announced on social media he would blockade the strategic Strait of Hormuz trade route that he has been demanding Tehran fully re-open, after Vice President JD Vance left negotiations with an Iranian delegation in Islamabad.
The U.S. military said the blockade would begin at 14:00 GMT and apply to all ships leaving or seeking to dock at Iranian ports on either side of the key waterway.
U.S. forces would not impede vessels transiting the Strait of Hormuz to and from non-Iranian ports, it added.
It was unclear, however, how the military would enforce such a blockade.
In a lengthy social media post on April 12, Trump said his goal was to clear the strait of mines and reopen it to all shipping, but that Iran must not be allowed to profit from controlling the waterway.
Nicole Grajewski, an assistant professor at Sciences Po's Center for International Research, said a US blockade was "not a minor coercive signal" but could rather be considered an effective resumption of the war.
Iran's military command issued a statement branding the upcoming blockade a criminal act of piracy and warned: "If the security of the Islamic Republic of Iran's ports in the waters of the Persian Gulf and the Arabian Sea is threatened, no port in the Persian Gulf and the Arabian Sea will be safe."
China, Washington's great power rival and a big importer of Iranian oil, also criticized the plan.
"The Strait of Hormuz is an important international trade route for goods and energy, and maintaining its security, stability, and unimpeded flow is in the common interest of the international community," Foreign Ministry spokesman Guo Jiakun said, urging Iran and the U.S. not to reignite the war.
Russia, Iran's main international ally, said Foreign Minister Sergei Lavrov would visit his Chinese counterpart Wang Yi in Beijing on April 14 and 15 this week.
Among Washington's NATO allies, much criticized by Trump for their reluctance to follow him to war, Spain's Defense Minister Margarita Robles said the planned naval blockade "makes no sense.”
And in a BBC radio interview, U.K. Prime Minister Keir Starmer said Britain will not join the U.S. blockade, adding the U.K. "is not getting dragged in" to the war with Iran.
