April 18, 2026
Iran reversed a brief reopening of the strategic Strait of Hormuz on Saturday, saying it would close the waterway again while the United States enforces a naval blockade of Iranian ports. Tehran’s military characterized the U.S. blockade as a breach of ceasefire understandings and said passage through the strait would require Iranian authorization.
The UK Maritime Trade Operations center reported that two gunboats linked to Iran’s Islamic Revolutionary Guard Corps fired on a tanker about 20 nautical miles northeast of Oman; the vessel and its crew were reported safe. According to the tanker’s captain, the warning shots were fired without a prior radio challenge.
Iran’s new supreme leader pledged the navy stood ready to inflict further defeats on adversaries, comments that followed the decision to close the strait. Parliament speaker Mohammad Bagher Ghalibaf warned the passage “will not remain open” if the blockade continues.
In Washington, President Donald Trump said the blockade would remain in place and cautioned he might not extend the ceasefire if a long-term deal with Iran is not reached by Wednesday. The U.S. administration also renewed, for roughly a month, a waiver permitting purchases of sanctioned Russian oil at sea — a move Moscow welcomed as stabilizing for energy markets. The waiver explicitly excludes transactions involving Iran, Cuba and North Korea and has drawn criticism from some U.S. lawmakers.
Diplomatic efforts to de-escalate continued. Egypt said it and partners Turkey, Pakistan and Saudi Arabia were coordinating to try to secure a final U.S.-Iran agreement “in the coming days.” Pakistani Prime Minister Shehbaz Sharif concluded a regional diplomatic tour that included Qatar, Saudi Arabia and Turkey; Pakistan has hosted talks between U.S. and Iranian interlocutors. Turkey and other regional actors have pushed for measures to contain the conflict and to negotiate a post-war security framework.
Separately, Iran said it had partially reopened eastern air routes for international flights and reopened several airports. Flight-tracking services, however, showed limited visible activity hours after the announcement.
The wider region also experienced related clashes and tensions. Lebanon’s prime minister condemned an attack on French UNIFIL peacekeepers in southern Lebanon; a UNIFIL spokesperson confirmed an incident in Ghandouriyeh but did not provide casualty details. The Israeli military said it had killed militants who crossed a de-facto “yellow line” in southern Lebanon, a new reference to the demarcation since the recent ceasefire. Germany’s interior minister said the Iran–U.S./Israel war had not yet produced a migration wave to Europe but that authorities remained cautious.
As diplomatic, security and energy pressures intersect, maritime traffic and global oil markets face continued vulnerability. Analysts warn further disruption is possible if the strait remains closed or if fighting intensifies, heightening risks to commercial shipping and energy supplies.