Situation in Strait of Hormuz after US blockade

Apr 16, 2026

The U.S. naval blockade of Iranian ports and ships in the Strait of Hormuz entered its fourth day, disrupting Iran-linked shipping and constraining commercial traffic through the critical waterway. The blockade targets Iran's $45 billion annual oil exports, which represent 13% of its GDP, with China purchasing up to 90% of Iran's seaborne crude including more than 500 million barrels last year. President Trump ordered the blockade to interdict vessels paying Iranian transit tolls of up to $2 million and teased further peace talks in Pakistan later this week. The action raises legal questions under UNCLOS Article 38, which guarantees immutable transit passage rights through international straits even during conflict, though the U.S. has not ratified the treaty. China warned against reverting to "the law of the jungle" while the UK refused U.S. use of its Diego Garcia base, highlighting international divisions over Trump's third unilateral naval blockade in the past year.

U.S. Blockade of Iranian Vessels in the Strait of Hormuz

▪President George H.W. Bush was the last U.S. President to green light a naval blockade before Trump, during the 1990-1991 Gulf War as part of U.N. sanctions enforcement.
▪President Trump vowed to interdict vessels paying Iranian transit tolls in the Strait of Hormuz.
▪Iran had been charging up to $2 million for safe passage to ships through the Strait of Hormuz.
▪China purchased up to 90% of Iran's seaborne crude in recent times, including more than 500 million barrels last year.
▪Iranian oil exports totaled approximately $45 billion last year, representing 13% of Iran's GDP.
▪The United Kingdom refused to allow the U.S. to use its military base in Diego Garcia to attack Iran.

Legal Framework and UNCLOS Implications for Maritime Norms

▪The United Nations Convention on the Law of the Sea has served as the foundational treaty establishing global legal standards for ocean usage, resource management, and maritime jurisdictions since 1994.
▪In 2013, retired PLA Senior Colonel Zhou Bo led a Chinese delegation to the Pentagon to attempt to resolve differences of interpretation regarding UNCLOS.
▪Under UNCLOS Article 38, the Strait of Hormuz is a strait used for international navigation where the right of transit passage is immutable, even during conflict.

China's Potential Use of U.S. Precedent Against Taiwan

▪China controls a shadow fleet of up to 200,000 fishing boats as an informal militia.
▪Taiwan is only recognized by 12 governments and is barred from the United Nations.
▪China controls the world's largest navy consisting of more than 370 battle force People's Liberation Army vessels.
▪Since June 2022, China has moved toward claiming the Taiwan Strait is internal waters, territorial sea, contiguous zone, and exclusive economic zone.
▪Taiwan is an import-reliant island of 24 million people.
▪Chinese President Xi Jinping warned alongside Abu Dhabi Crown Prince Khaled bin Mohamed in Beijing on Tuesday that the world must not revert to the law of the jungle.
▪On December 29, China launched its most extensive military drills around Taiwan, involving more than 200 aircraft and dozens of naval and coastguard vessels simulating a total blockade of the island.

Perspective of China

▪China's purchase of up to 90% of Iran's seaborne crude oil makes it the primary economic stakeholder affected by the U.S. blockade in the Strait of Hormuz.

Perspective of Iran

▪Iran's practice of charging up to $2 million for safe passage through the Strait of Hormuz was cited by President Trump as justification for interdicting vessels.
▪The U.S. blockade threatens Iran's $45 billion in annual oil exports, which represent 13% of Iran's GDP.

Perspective of United Kingdom

▪The United Kingdom's refusal to allow the U.S. to use Diego Garcia military base represents a significant allied disagreement over the Iran blockade strategy.