U.S. officials told The New York Times that Iran began laying mines in the Strait of Hormuz on Thursday, a vital maritime route through which about 20 percent of global oil supply—around 31 million barrels of crude daily—passes. The move reportedly surprised the Trump administration, even as President Donald Trump publicly claimed that U.S. forces had destroyed Iran’s navy.

According to CNN, senior Trump administration officials privately told lawmakers that they had not previously considered the possibility of Iran closing the strait in response to U.S. and Israeli attacks. A former U.S. official who served under both Republican and Democratic administrations said that planning to prevent such a scenario had long been a core principle of U.S. national security policy, expressing astonishment that the administration had not prepared for it.

The incident underscores the strategic vulnerability of the Strait of Hormuz and raises concerns about potential disruptions to global oil markets if tensions escalate further.