The questions piling up after a counter-terror swoop at RAF Fairford

Five men have been arrested and a major incident declared near RAF Fairford in Gloucestershire after police were alerted to "suspicious vehicles" heading towards the airbase, in a case that has opened a fresh security question for the government: how well prepared was Britain for an attack on one of its most exposed military sites?

The base sits at the centre of an unusually sensitive military story. RAF Fairford has been a forward operating base for the US Air Force since the Cold War, a piece of American infrastructure in the English countryside. Its two-mile runway is so exceptionally long that it once served as an emergency landing site for the US space shuttle programme. Today, it has acquired a second reputation of comparable strategic weight: it is the principal launchpad for the heavy bombers President Donald Trump has used to strike Iran, and the only base in Europe with the capability to support such operations from British soil.

That status is precisely what makes Fairford a potential target, and it is a point acknowledged openly in the article of the threat itself. Analysts note that the base's high profile is not incidental but central to the risk profile — a facility that cannot be replicated or easily relocated cannot easily be defended out of the spotlight.

Iran has made its position unusually explicit. In July, Tehran's foreign ministry accused the UK of being complicit in war crimes by permitting the US to use Fairford as a staging post for strikes against Iran, and issued a blunt warning that any state taking part in military aggression against the country would carry responsibility for the fallout. Western officials and commentators alike read the language as a direct, named threat against British territory.

The diplomatic picture offers little reassurance. Efforts to end the war remain deadlocked, and that impasse has fuelled speculation that Tehran might be contemplating raising the pressure on Washington — potentially through an attack far from the Middle East — in an attempt to influence the political calculus ahead of the US midterm elections in November.

Britain's own response has been to talk tough. When Foreign Secretary Ed Miliband met his Iranian counterpart Abbas Araghchi at the United Nations last week, he pointedly warned of the UK's unwavering resolve to act against threats from Iranian-linked groups, and said hostile activity on British soil would not be tolerated. The timing of those remarks, days before the arrests, suggests ministers were already braced for exactly this kind of scenario — or were seeking to deter it.

Attention has not focused on Tehran alone, however. Moscow is also in the frame, and with some justification. Danish intelligence warned last week that Russia could, in the coming months, carry out a limited military attack against a Nato member state — a warning consistent with a pattern of hybrid activity on the continent's eastern flank. Germany has already formally accused Russia of deploying an explosive-laden drone in an attempted attack on Leipzig in August. Over the summer, Russia's embassy in London issued its own pointed caution about Britain's support for Kyiv, warning that the deeper British involvement in the conflict, and the greater its backing for what it called Ukraine's "terrorist machinery", the higher the price the UK would pay. That, too, was read in Whitehall and elsewhere as something closer to a threat than a warning.

Beyond state actors, authorities have also had to consider the unpredictable: the possibility of an Islamist attack, or a direct-action-style incident carried out by a group fiercely opposed both to the US-Israeli campaign against Iran and to the use of UK bases to support it. Counter-terrorism specialists stress that such a spectrum of threats is difficult to separate in advance, and that a small, well-prepared group could produce a large and frightening disruption without any state hand visible at all.

So far, the picture of the response is incomplete and contested. The division of responsibility is clear in principle — the US guards the inside of the base, while UK authorities are tasked with countering threats outside the perimeter — but the question of what was known, and when, is unresolved. President Trump said the suspects had been under investigation for a long time, an assertion that implies a long-running operation rather than an improvisation. Others have suggested the incident may have been interrupted largely because a passing motorist took it upon himself to report unusual vans to the police — a scenario that would say more about luck and public vigilance than about intelligence-led disruption.

The Ministry of Defence, for its part, has leaned on a general assurance, with a spokesman saying Britain's armed forces remain ready to keep the country safe from attacks whether on home soil or from abroad, and that the UK stands ready around the clock to defend itself. Such statements, while reassuring, do not answer the questions investigators will need to answer: whether a hostile foreign state was involved or whether proxies acted on its behalf; what the suspects intended; and what the potential danger was to residents in the surrounding area.

What the episode does establish, officials and commentators agree, is that the risks generated by conflicts far from Britain do not remain far from it. A base built for bombers, and now central to an active campaign, sits in open countryside a short drive from towns and villages — a reminder that the geography of modern conflict reaches much further than the front lines suggest.

For now, then, the story is one of an investigation at an early stage and an information gap that the authorities have not yet begun to close. The questions — about intent, sponsorship and preparedness — will be far harder to answer than the arrests themselves.