Secretary of State Michael Pompeo announced Thursday that the United States has assessed that Iran is responsible for attacks on two oil tankers earlier that morning in the Gulf of Oman.

“It is the assessment of the United States government that the Islamic Republic of Iran was responsible for the attacks that occurred in the Gulf of Oman today,” he said at a State Department briefing.

Pompeo said the assessment was based on intelligence, the weapons used, the level of expertise needed to execute the operation, recent similar Iranian attacks on shipping, and “the fact that no proxy groups operating in the area have the resources and proficiency to act with such a high degree of sophistication.”

Pompeo said Thursday’s attack was only “the latest in a series of attacks” by Iran against “American and allied interests.”

He said on April 22, 2019, Iran promised to interrupt the flow of oil through the Strait of Hormuz. “It is now working to execute on that promise,” he said.

The secretary said in early May the Iranian Revolutionary Guard Corps attempted a “covert deployment of modified dhows capable of launching missiles,” and on May 12, 2019, Iran attacked four commercial ships near the Strait of Hormuz.

On May 14, 2019, he said Iran-backed surrogates attacked by armed drones struck two strategically important pipelines in Saudi Arabia.

He also listed a rocket landing near the U.S. embassy in Baghdad’s Green Zone, but did not attribute it specifically to Iran.

Pompeo also said on May 31, 2019, a car bomb in Afghanistan wounded four U.S. service members, killed four Afghan civilians, and wounded bystanders. He did not attribute it specifically to Iran either.

Just yesterday, he said, Iranian surrogates fired a missile into Saudi Arabia, striking the arrivals terminal of an international airport and wounding 26 people.

“Taken as a whole, these unprovoked attacks present a clear threat to international peace and security, a blatant assault on freedom of navigation, and an unacceptable campaign of escalating tension by Iran,” he said.

Pompeo noted that Japanese Prime Minister Abe Shinzo made a historic trip to Iran to ask for deescalation and enter into talks. Pompeo said Abe was rebuffed, and Iran insulted Japan by attacking a Japanese oil tanker just outside of Iranian waters, threatening the lives of the entire crew and creating a maritime emergency.

Pompeo’s statement was a swift and rare public attribution for the attacks on Thursday that the U.S. government had avoided during the previous incidents.

He argued that Iran was lashing out in response to the U.S.’s maximum pressure campaign, aimed at cutting off Iran’s sources of revenue to drive them back to the negotiating table on their illegal nuclear program.

“Iran is lashing out, because the regime wants our successful maximum pressure campaign lifted. No economic sanctions entitled the Islamic Republic to attack innocent civilians, disrupt global oil markets, and engage in nuclear blackmail,” he said.

“The international community condemn’s Iran’s assault on freedom of navigation and the targeting of innocent civilians,” he added.

He said he has instructed the acting U.S. Ambassador to the United Nations, Jonathan Cohen, to raise Iran’s attacks in a United Nations Security Council meeting Thursday afternoon.

Pompeo said the U.S. policy remained an “economic and diplomatic effort” to bring Iran back to the negotiating table at the right time, to encourage a comprehensive deal that addresses the “broad range of threats.”

“Iran should meet diplomacy with diplomacy, not with terror, bloodshed, and extortion,” he said.

However, he issued a warning.

“The United States will defend its forces, interests, and stand with our partners and allies to safeguard global commerce and regional stability. And we call on nations threatened by Iran’s provocative acts to join us in that endeavor,” he said.

U.S. Central Command confirmed the attacks occurred in a statement.

“U.S. Naval Forces in the region received two separate distress calls at 6:12a.m. local time and a second one at 7:00 a.m. U.S. Naval Forces Central Command received the calls from the M/V Front Altair and M/V Kokuka Courageous, who were operating in international waters of the Gulf of Oman,” said Centcom spokesman Lt. Col. Earl Brown.

“USS Bainbridge (DDG 96) was operating in the vicinity and provided immediate assistance to the M/V Kokuka Courageous. Twenty-one mariners from the M/V Kokuka Courageous, who abandoned ship, are currently aboard USS Bainbridge. A Navy P-8 is also providing support.”