Iran's Islamic Revolutionary Guard Corps (IRGC) Navy closed the Strait of Hormuz and fired on ships attempting to transit the waterway on April 18, 2026 [1, 2].
This escalation threatens global energy security and maritime trade, as the strait is one of the world's most critical oil transit chokepoints. The move signals a sharp increase in tensions between Tehran and Washington over ongoing naval confrontations.
IRGC Navy gunboats targeted tankers and ships attempting to navigate the waters off the coast of Oman [1, 2]. The IRGC Navy said that ships approaching the vital waterway "will be targeted" [1].
Tehran described the closure and the attacks as retaliation for a blockade of Iranian ports currently maintained by the United States [1, 5]. The IRGC Navy issued a directive stating, "No vessel should make any movement from its anchorage in the Persian Gulf and the Sea of Oman, and approaching the Strait of Hormuz will be considered as cooperation with the enemy" [5].
President Donald Trump responded to the closure by saying the United States won't be "blackmailed" [1]. The administration's stance suggests a refusal to lift port restrictions in exchange for the reopening of the strait.
The IRGC Navy continues to monitor the Persian Gulf and the Sea of Oman to enforce the restrictions [1, 2]. The U.S. has not announced a specific military counter-operation but maintains its blockade of Iranian ports [1, 5].
“Ships approaching the vital waterway "will be targeted".”
The closure of the Strait of Hormuz represents a high-stakes escalation of the 'maximum pressure' cycle between the U.S. and Iran. By weaponizing the waterway, Iran is attempting to leverage global oil market volatility to force a U.S. withdrawal from Iranian ports. Conversely, the Trump administration's refusal to yield suggests a strategy of containment that risks direct military conflict in the Persian Gulf.
