UK counter-terrorism police on Tuesday arrested two more men on suspicion of helping Iranian intelligence in an alleged plot against RAF Fairford air base. Police now say plainly that they suspect Iran of being involved.
The first five people were arrested just after midnight on 27 September, 320 metres from the base in Gloucestershire. They were released on bail the next day.
What happened before: Attack on UK base foiled after suspect called 999
The new arrests are under the National Security Act. One of the men is a 24-year-old British citizen, who was among the first five. The other is 25, holds both British and Iranian citizenship, and was arrested in central London a few days after the incident. Both had been released on bail before Tuesday's arrest. The first arrests were on suspicion of breaching the Explosive Substances Act.
Seven people have been held in the case in all: five at the scene and two in the following days. The five who were not re-arrested on Tuesday remain on bail. No one has been charged.
Detectives are checking whether people in the UK acted for Iranian services, how big a role Iran played and what the aim was. Police call the case highly complex and are following several lines of inquiry.
Assistant commissioner Laurence Taylor, who leads National Counter Terrorism Policing, said the inquiry is moving fast and evidence is being gathered. Police have not changed their view: "We consider it highly likely that there is Iranian state involvement." He said detectives increasingly suspect a link to Tehran. Taylor admitted that people have questions that remain unanswered, and promised maximum openness.
Last week, UK prime minister Andy Burnham said Iran probably coordinated the suspicious activity near the base. Iran's ambassador to the UK rejected the claim, and Tehran has denied any link to the case before. After the first arrests, the Iranian embassy in London condemned "malicious and baseless speculation" and accused those who tie Iran to the incident of stirring up anti-Iranian feeling in Britain.
The base in south-west England is British, but the US air force uses it as a forward base. B-1 bombers flew from there in strikes on Iranian targets this year. In July, Tehran threatened to attack bases such as Fairford if US aircraft keep taking off from them for operations against Iran. After the incident, the US pulled the bombers out of the base over security fears.
US president Donald Trump welcomed the arrests and said British and US authorities had worked together. He said the men had been under joint watch for a long time and wanted to do major damage to the base.
A local farmer driving home from a party raised the alarm. Shortly after midnight she saw three vans blocking a country road near the base, and several masked men acting suspiciously. When she turned her car round, the men scattered across fields and into trees, some towards the base. She called the emergency services at once and warned her neighbours in a local WhatsApp group. Police arrived within minutes and arrested the first five.
Police declared a "major incident". Armed officers and military bomb disposal teams came to the scene, dozens of residents were evacuated, and road closures around the base were still in place on 29 September.
The first reports said there were explosives in the vans, which sparked fears of an imminent attack. Police later said no explosives were found. The three vans held petrol, which police described as an accelerant. The vans carried suspicious company logos and phone numbers. UK fuel delivery firm Fuel2U denies any link to them.
Defence secretary Wes Streeting praised the farmer. "She did exactly what we would hope someone in such an unusual situation would do, and I am sincerely grateful to her," he said. Streeting said her account does not cover everything the authorities know, and she has only a "partial picture" of events.
The farmer believes her actions in effect foiled the men's plans. She is unhappy that investigators have not contacted her for further questioning.