DUBAI, United Arab Emirates — An oil pipeline that runs across Saudi Arabia was hit by drones Tuesday west of its capital of Riyadh, the Saudi energy minister said, shortly after rebels in Yemen claimed they carried out coordinated drone strikes against the kingdom.

The attacks followed reports of sabotage against oil tankers in the Persian Gulf off the coast of the United Arab Emirates on Sunday, with tensions rising between the U.S. and Iran.

Oil prices rose Tuesday, with benchmark Brent crude trading over $71 a barrel, up more than $1 on the day.

Saudi Energy Minister Khalid al-Falih Al-Falih vowed that production and export of Saudi oil would not be interrupted. In a statement carried by the state-run Saudi Press Agency, he called the pipeline attack “cowardly,” saying that recent acts of sabotage against the kingdom’s vital installations were targeting not only Saudi Arabia, but also the safety of the world’s energy supply and global economy.

Yemen’s Houthi rebels said they launched seven drones against vital installations in Saudi Arabia, which borders Yemen to the north. Saudi Arabia has been at war with the Houthis and their allies in Yemen since March 2015, targeting the Iranian-allied rebels with near daily airstrikes.

“This is a message to Saudi Arabia: Stop your aggression,” Houthi spokesman Mohammed Abdel-Salam told The Associated Press. “Our goal is to respond to the crimes they are committing every day against the Yemeni people.”

Drones Had Targeted Petroleum Pumping Stations

The two oil pumping stations targeted in Saudi Arabia are over 500 miles from Yemen’s northern border with the kingdom. It wasn’t immediately known where the Houthis launched the drones.

The attacks demonstrated the increased risks in a region vital to global energy supplies amid heightened tensions following the Trump administration’s withdrawal from the 2015 nuclear deal between Iran and world powers, and the subsequent reimposition of U.S. sanctions to cripple the Iranian economy. Iran has since said it would begin enriching uranium at higher levels by July 7 if world powers failed to negotiate new terms for the deal.

Al-Falih said the drone attacks reaffirm the need of the international community to confront the activities of groups like the Houthis, whom he accused of being backed by Iran, Saudi Arabia’s regional rival.

He said the drones had targeted petroleum pumping stations supplying a pipeline running from its oil-rich Eastern Province to the Yanbu Port on the Red Sea.

Saudi Aramco, the government-controlled oil company, said that as a precaution, it temporarily shut down the East-West Pipeline and contained the fire, which caused minor damage to one pumping station. It added that Saudi Aramco’s oil and gas supplies have not been affected by the attack.

Saudi Arabia said the two petroleum pumping stations that were struck by drones are located in the greater region of Riyadh, home to the landlocked capital. The stations, targeted around the same time early Tuesday, are located in al-Duadmi and Afif, about 125 miles west of Riyadh city and 250 miles west of Riyadh city, respectively.

Saudi Arabia built its pipeline in the 1980s amid fears that the Iran-Iraq war would cut off shipping traffic through the Strait of Hormuz. The 746-mile pipeline is actually two pipes that have a total capacity of 4.8 million barrels of crude oil a day, according to the U.S. Energy Information Administration.

Suspicious Activities and Sabotage in the Region

The four oil tankers that were targeted Sunday off the coast of the UAE’s port of Fujairah were allegedly damaged in what Gulf officials described as sabotage, although satellite images obtained Tuesday by the AP showed no visible damage to the vessels.

The MT Andrea Victory, one of the alleged targets, sustained a hole in its hull just above its waterline from “an unknown object,” its owner Thome Ship Management said in a statement. Images Monday of the Norwegian-flagged Andrea Victory, which the company said was “not in any danger of sinking,” showed damage similar to what the firm described.

Details of the alleged sabotage to two Saudi, one Norwegian and one Emirati oil tanker remain unclear, and Gulf officials have refused to say who they suspected was responsible.

Satellite images provided to the AP by Colorado-based Maxar Technologies showed a boom surrounding the Emirati oil tanker A. Michel, indicating the possibility of an oil leak. The other three showed no visible damage from above.

A U.S. official in Washington, without offering any evidence, told the AP that a U.S. military team’s initial assessment indicated Iran or Iranian allies used explosives to blow holes in the ships. The official was not authorized to discuss the investigation and thus spoke on condition of anonymity.

The U.S. has recently warned ships that “Iran or its proxies” could be targeting maritime traffic in the region. Washington has deployed an aircraft carrier, the USS Abraham Lincoln, and B-52 bombers to the Persian Gulf to counter alleged, still-unspecified threats from Tehran.

Speaking in New Delhi, Iran’s Foreign Minister Mohammad Javad said he spoke with Indian officials about concerns of “suspicious activities and sabotage in the region.”

Drone Strikes Reflect How Houthis Have Expanded Their Capabilities

“We announced that we had previously predicted these sorts of activities aimed at escalating tension in the region,” he said.

United Nations deputy spokesman Farhan Haq called on “all concerned parties to exercise restraint for the sake of regional peace, including by ensuring maritime security.”

On Tuesday, Spain temporarily pulled one of its frigates that was part of a U.S.-led combat fleet from near the Persian Gulf because of the mounting tensions. The Ministry of Defense said the Méndez Núñez, with 215 sailors aboard, will not cross the Strait of Hormuz into the Gulf with the USS Abraham Lincoln. The Spanish frigate was the only non-U.S. vessel in the fleet.

The drone strikes on Saudi oil facilities reflect how the Houthis have expanded their capabilities during the four-year war. The rebels have targeted Riyadh with missiles and used drones to disrupt air traffic at Saudi airports near the Yemen border.

The Houthis also have flown into the radar arrays of Saudi Arabia’s Patriot missile batteries, according to the research group Conflict Armament Research, disabling them and allowing the rebels to fire ballistic missiles into the kingdom unchallenged.

Iran has been accused by the U.S. and the U.N. of supplying ballistic missile technology and arms to the Houthis, which Tehran denies.

Such drones remain difficult to shoot down with either light or heavy weapons. Iraqi forces learned this from driving out the Islamic State group from northern Iraq, where the extremists would load drones with grenades or simple explosives to target their forces.

The U.S. supports Saudi Arabia and its allies in the war against the Houthis, despite criticism that Saudi-led coalition airstrikes have killed civilians.