U.S. Navy warships stationed in the Persian Gulf region have increased their patrols through the Strait of Hormuz, the busy merchant ship passageway, in response to recent moves by Iran to seize two oil tankers, the latest sign of rising tensions between Iran and the United States.
“Iran’s actions are unacceptable,” Vice Adm. Brad Cooper, the commander of U.S. naval forces in the region, said in an interview on Monday at the Navy base here in Bahrain. He was speaking several days after he rode a Navy guided-missile destroyer through the strait of Hormuz, along with leaders from the French and British navies, in an effort to send a unified message to Iran.
Iran has “harassed, attacked or interfered” with 15 internationally flagged merchant ships since 2021, Pentagon and White House officials said this month, as they announced the move to increase patrols by U.S. Navy ships, drones and planes, as well as those of United States allies in the region.
Most recently, Iran’s Navy flew a helicopter over the deck of an oil tanker named Advantage Sweet in late April. The Marshall Islands-flagged ship had been chartered by Chevron, on its way to Houston from Kuwait, and according to Lloyd’s List, which tracks shipping, was carrying 750,000 barrels of crude oil.
Commandos from Iran’s Islamic Revolutionary Guard Corps lowered themselves to the Advantage Sweet’s deck via a rope and seized control of the vessel just after it had passed through the Strait of Hormuz. Iran then showed a celebratory video of the seizure on state television.
Six days later, a dozen speedboats from the Iranian navy surrounded a second oil tanker, this time the Panama-flagged Niovi, after it left a dry dock in Dubai, on its way to another port in the United Arab Emirates. The ship was forced to divert to Iranian territorial waters.
The United States “will not allow foreign or regional powers to jeopardize freedom of navigation in the Middle East waterways, including the Strait of Hormuz,” John Kirby, a spokesman for the White House National Security Council, said when he announced the increased U.S. Navy patrols earlier this month.
The Strait of Hormuz, which is bordered by the United Arab Emirates and Oman on one side and Iran on the other, is as narrow as 21 miles. But it sees constant merchant ship traffic, particularly among oil tankers that supply oil to the world.
The plan, at least for now, is not to send additional Navy ships or planes to the region, Pentagon officials said, but instead to move those already in the area through the Strait of Hormuz more frequently, to send a signal to Iran that the United States and its allies are watching, and to be in closer proximity if other incidents take place, said Cmdr. Timothy Hawkins, a spokesman for the Navy’s Fifth Fleet based in Bahrain.
The Navy Fifth Fleet’s operations cover 2.5 million square miles of water, from the Persian Gulf to parts of the Indian Ocean, and more of its vessels will now be focused in the area around Iran.
“It is sort of like when you rotate more patrols cars on a highway,” Commander Hawkins said. “They get off the exit and turn back around, and keep doing these loops.”
On Tuesday, a U.S. Coast Guard cutter, preceded by a drone vessel that the Navy operates in the Persian Gulf, sailed through the Strait of Hormuz, along with the U.S.S. Paul Hamilton, the guided-missile destroyer, which had also made the same trip on Friday.
In response to the recent moves by the United States, Iran has argued that its action against the two merchant ships came after they both violated international maritime regulations, including the Advantage Sweet, which Iranian officials assert had collided with an Iranian boat, injuring crew members.
“The Islamic Republic of Iran considers the continued presence of foreign military forces in the waters of the Persian Gulf as a threat to the security of navigation in this strategic waterway and believes that the countries of the region have the ability to protect the peace and security of navigation in it without the presence of foreigners,” Nasser Kanani, a spokesman for Iran’s Ministry of Foreign Affairs, said in a statement.
In April, just before Iran seized the Advantage Sweet oil tanker on its way to Houston, the United States intercepted a ship carrying Iranian oil that the government asserts was violating sanctions, according to Ambrey, a marine intelligence firm, as first reported by The Financial Times. The U.S. authorities said the seizure had been authorized under a court order.
Dating to at least the mid-1980s — when there was a period nicknamed the Tanker War because of a series of attacks by Iran on merchant ships in the Strait of Hormuz — there have been cycles of escalation in the region as the ship intercepts by Iran have intensified or waned.
There is always a risk that the sparring between the United States and Iran could quickly turn into a conflict, but both countries want to avoid such an outcome, experts on the region say, as do U.S. Navy officials.
“It is almost like Kabuki theater that both countries have engaged in for a very long time, even if the reality of serious armed conflict is close to unthinkable for both nations,” said John Ghazvinian, the director of the Middle East Center at the University of Pennsylvania and the author of a book on the history of relations between Iran and the United States.
But the animosity between the two nations has increased over the past several years. Two ship crew members were killed in July 2021 when an Iranian-built drone, armed with explosives, attacked the merchant ship named Mercer Street, off Oman, an incident that American and European officials said they believed Iran was behind.
The United States had already been using its Navy and Coast Guard ships in the region to look for weapons and drugs being sent through the Persian Gulf, as Iran has been accused of helping arm its allies in Yemen, Syria and Lebanon, and more recently, of sending its attack drones to Russia, where they have been used to attack Ukraine.
Tensions have also intensified since the Trump administration withdrawal in 2018 of the United States from a nuclear deal with Iran, which then moved again to start enriching its uranium supply closer to levels needed to make a nuclear weapon.
The Pentagon announced in April that it was extending the tour of the aircraft carrier George H.W. Bush in the eastern Mediterranean and speeding up the deployment of Air Force A-10 attack planes to a base in the Middle East. It also made the rare public announcement that the United States was sending a guided-missile submarine to the Middle East.
Mr. Ghazvinian said the recent actions by the Pentagon could be an effort to reassert U.S. relevance in the region, after China in March stepped in to help negotiate a diplomatic rapprochement between Saudi Arabia and Iran. Some Gulf Arab officials said China’s growing presence suggested they could no longer rely on the United States to guarantee their security.
Commander Hawkins, the Navy spokesman, said both the United States and Iran had the right to patrol the Persian Gulf and the Strait of Hormuz, and have been doing so for decades.
Eric Schmitt contributed reporting from Washington.