Yemen’s Tehran-backed Houthis attacked four cities in the south of U.S. ally Saudi Arabia on Tuesday, wounding more than 70 people and setting oil installations ablaze in what appeared to be a major expansion of the six-month-old Middle East war.

Meanwhile, U.S. forces struck multiple Iranian tankers tied to the Islamic Revolutionary Guard Corps in response to Iranian attempts to hit a U.S. Navy warship, a U.S. official said, marking a resumption of U.S. attacks on Iran after a two-day pause.

Iranian media reported multiple attacks, with the Tasnim news agency saying a U.S. missile struck an Iranian tanker six kilometres from the oil hub of Kharg Island, and the state broadcaster reporting that the U.S. attacked a second oil tanker near the waters of Jask on the Gulf of Oman.

The IRGC threatened to target oil tankers in Kuwaiti and Bahraini ports in response, warning crews there to evacuate, according to a statement carried by state media.

In Saudi Arabia, the Houthis, who control most of Yemen’s populated areas including the capital, said they had launched a broad operation deep into Saudi territory.

They used drones and missiles to strike a Saudi airbase in the southern city of Khamis Mushait as well as Saudi state oil company assets in the cities of Abha, Najran and Jazan.

NASA satellite images showed a thick cloud of black smoke over the Jazan refinery and a column of white smoke rising from an oil distribution centre in Abha.

Saudi authorities described blazes at the sites and said women and children were among the 73 people hurt.

The reports of such large numbers of wounded suggested the attacks were among the biggest carried out against Saudi Arabia since the United States and Israel launched their war against Iran in February.

No confirmed images from the ground of the attacked Saudi cities were available, and witnesses could not be reached in a country where media is tightly controlled.

(Reuters/NAN)