New Tensions Build Between U.S. and Iran in Waters Off Yemen

The U.S. military and its Saudi allies are preparing for another potential showdown with Iran in the Gulf of Aden over the fate of a cargo ship said to be carrying aid for Yemen.

Two Iranian warships have linked up in the waters off Yemen’s coast with an Iranian vessel believed to be carrying humanitarian aid for civilians caught in Saudi Arabia’s two-month-old bombing campaign against Iran-backed Houthi rebels who have seized control of Yemen’s capital and government, Pentagon officials said Tuesday.

That has raised concerns that Iran will ignore international pressure and send the ship directly to Yemen without agreeing to United Nations inspections. If Iran defies the U.N. and U.S., it could set the stage for a showdown in which Saudi ships might try to block the flotilla from reaching Yemen.

The U.S. military, which has 14 warships at sea in the region, is keeping a close eye on the Iranian ships scheduled to arrive in the western Yemeni port of Hodeida on Thursday, according to Iran’s official Islamic Republic News Agency.

American officials have called on Iran to send the ship to the African country of Djibouti to undergo newly established U.N. inspections for aid going to Yemen. But Iran has ignored that appeal so far.

Iranian Foreign Ministry spokeswoman Marziyeh Afkham said last week that Yemen aid efforts would be “in full harmony” with the U.N., but she didn’t say whether that meant the ship would go to Djibouti. If Iran refuses to send its aid ship to Djibouti, Saudi and U.S. officials would have to decide whether to try to confront the Iranian flotilla at sea.

“Just getting them to go to Djibouti and...inspected would be considered a victory for the U.N. way of doing things because Iran’s not flouting international agreements and it keeps everyone away from these potentially dangerous showdowns,” said one senior U.S. defense official.

U.S. warships aren't expected to directly confront Iran. An attempt to search the Iranian boat would likely be done by Saudi Arabia or Egypt.

“The thing that would cause the most problems is if the Saudis boarded it,” the defense official said.

If Iran refuses to comply, the U.S., U.N. and Saudi Arabia could try to inspect the aid ship when it gets to port in Yemen.

The standoff over the aid ship is the latest indication of tensions mounting between Iran and Saudi Arabia, the two main powers in the Persian Gulf region.

Last month, the U.S. military sent an aircraft carrier into the Gulf of Aden to deter Iran from sending a flotilla suspected of carrying arms for the Houthi rebels targeted by the Saudi airstrikes. Iran turned the ships around and averted a potential confrontation.

Soon after, Iranian patrol boats stepped up their harassment of commercial ships traveling through the strategic Strait of Hormuz and seized one Marshall Islands-flagged vessel over what Tehran said was a business dispute. In response, for several days, the U.S. Navy started providing extra protection for American and British ships traveling through the narrow strait—a key oil shipping route between Oman and Iran.

Iran and Saudi Arabia have long been at odds. But Saudi Arabia’s military campaign in Yemen, coupled with Iran’s negotiations with six world powers over its nuclear program, have fanned the rivalry.

Saudi Arabia is leading the campaign of airstrikes to the Houthis from power. And with the nuclear deal, which would remove international sanctions on Iran in exchange for limits on its nuclear activities—Iran may be able to exercise its influence more widely, posing a challenge to Saudi Arabia.

Since the Saudi-led coalition began its airstrikes on March 26, it has turned back two Iranian planes carrying aid to the country, according to Iranian state media. In one of the cases, Saudi jets bombed a runway at the airport in the Yemeni capital of San’a to prevent the Iranian plane from landing, Iranian media reported.

In early April, Iran dispatched its 34th Flotilla—the same one that is accompanying the aid ship—to the Gulf of Aden. Although Iranian officials described it as a routine anti-piracy deployment, it appeared to raise the potential for a conflict at sea with the Saudi coalition, which has been imposing an air and sea blockade on Yemen.

Write to Dion Nissenbaum at [email protected] and Asa Fitch at [email protected]