Britain imposed sanctions Monday on two individuals accused of conducting espionage and attacks for the Iranian government and formally reprimanded Tehran’s ambassador in London, according to statements from Foreign Secretary Ed Miliband and Home Secretary Shabana Mahmood. Prime Minister Andy Burnham told parliament the same day that the UK assessment is that Iran’s military “almost certainly” directed the terror plot suspected in September at RAF Fairford, an air base used by the U.S. military to launch attacks on Iran.

The sanctions, ambassador summons and a joint statement by the United States, Britain and other European allies mark the public British and allied response to the September incident, which took place after midnight Sept. 27 in Whelford, near the air force base. Britain has released few details; no one has been charged and the seven men arrested have been released.

Burnham told parliament: “I can confirm that our assessment that it is highly likely to have been coordinated in Iran, almost certainly directed by Iran’s Islamic Revolutionary Guards.” The Guardian reported that Burnham said there would be more sanctions against Iran.

Mahmood said Miliband spoke to Iran’s ambassador to Britain and imposed sanctions on two people accused of spying. i24 News reported that the ambassador was given an official reprimand for “malign activity.”

“[Miliband] will condemn Iran’s continued attempts to undermine our safety,” Mahmood said. “We are also sanctioning two individuals involved in conducting espionage and attacks on behalf of the government of Iran in Europe and the U.S., and we will not hesitate to take further action to restrict Iran’s capacity to threaten international security.”

The Guardian reported that a joint statement issued by the United States, Britain and other European allies, released by Britain’s Foreign Office, said it “has also concluded this event demonstrates the [Islamic Revolutionary Guard Corps’] continued willingness to project hostile activity beyond its borders through covert networks and proxy actors.”

The statement also linked Iranian agents to recent attacks throughout Europe targeting Iranian journalists, Jewish communities and U.S. interests.

The United States withdrew 12 B-1 bombers about a week after the incident amid concerns about drone attacks.