Why this mattersSo here's why RAF Fairford matters.
It's in Gloucestershire. It's where the US Air Force keeps the B-1 bombers it has used to bomb Iran, in the war between the two countries.
And the bombers aren't even there any more. America pulled them out on security grounds, about a month ago, right after the first arrests.
This all started on 27 September. Five British men, aged 23 to 25, were arrested near the base. Three suspicious vans had been spotted heading towards it. Police declared a major incident and evacuated around 85 households.
Army bomb disposal searched the vans. They found petrol, which police called an accelerant. No viable explosive.
One of those arrested, a 25-year-old UK-Iranian national, was re-arrested in October. He was released without charge. He's still on police bail.
Now, the Prime Minister's language has changed over time. On 1 October, Andy Burnham said there were strong signs that Iran had played a part.
Iran's embassy in London rejected that straight away. Abbas Araghchi, Iran's Foreign Minister, said Britain was barking up the wrong tree, pointing out that suspects had been let out on bail.
Marco Rubio, the US Secretary of State, said the plot clearly involved a foreign actor. He didn't name one.
Then on 12 October, Burnham went further in Parliament. He says quote "almost certainly directed by Iran's Islamic Revolutionary Guard".
That's the Prime Minister going from suspicion to direct blame, on the record, in the House of Commons.
The same day, Britain sanctioned two Iranian nationals. One of them, Ruhollah Bazghandi, is described as the head of counterespionage operations for the IRGC. Ed Miliband, the Foreign Secretary, called in Iran's ambassador. Almost 30 countries, including America, Canada, France and Germany, signed a joint statement condemning Iran's attacks on them and their partners.
Iran has denied state involvement the whole way through. It hasn't responded to today's charges yet.
Here's what we still don't know. What either man actually did. When they're next in court. Whether more of the men arrested in September get charged. And whether America's bombers ever come back to RAF Fairford.
Two men are now formally accused of helping Iran get close to a British base used to bomb Iran. From here, it's a courtroom. And most of what this investigation actually found still hasn't come out.
