Federal prosecutors in New York have charged three men with terrorism offences over what they describe as an Iran-backed campaign of nearly 20 attacks and attempted attacks across Europe and the United States, including a September plot against a British air base where American forces were stationed. The eight-count superseding indictment was unsealed on Tuesday.

The men are Mohammad Baqer Saad Dawood Al-Saadi, 32, who holds Iranian and Iraqi citizenship; Mohsen Mohajeri, 48, an Iranian; and Mohammed Ali Al-Hassani, 35, an Iraqi. Prosecutors allege they acted on behalf of Iran's Islamic Revolutionary Guard Corps and the Iraqi militia Kata'ib Hezbollah, both designated foreign terrorist organisations by Washington.

According to the indictment, Al-Hassani — operating from Iran — orchestrated the plot against RAF Fairford in Gloucestershire, paying associates in Britain from August to film the perimeter of the base, which serves as a forward operating base for the U.S. Air Force Global Strike Command. On September 26, three vans set off toward the base, and British police stopped them, according to the Jerusalem Post.

Al-Saadi, a longtime operative of the IRGC and Kata'ib Hezbollah, was already jailed in New York awaiting trial on terrorism charges filed in May. Prosecutors allege he tried to coordinate with Al-Hassani and Mohajeri from his cell by passing coded messages through intermediaries. He is accused of involvement in planning and promoting about 18 attacks in Europe. Prosecutors have not disclosed the whereabouts of Mohajeri and Al-Hassani.

The charges include conspiracy to provide material support to terrorist groups, conspiring and providing material support for acts of terrorism, and conspiring to bomb a place of public use. The case has been assigned to U.S. District Judge Colleen McMahon.

FBI Director Kash Patel said the case showed Iran's determination to carry out attacks in Europe and the United States. Iran has strongly denied any involvement. The United States evacuated B-1B bombers from RAF Fairford after the alleged plot came to light, and the British government has since said Iran was responsible for the incident.