As you presumably know five men were arrested outside RAF Fairford in the United Kingdom on charges of offenses under the explosives act and terrorism and later released on bail. It may be that is all, indeed, that is known about the incident or the authorities are merely being circumspect.
That hasn’t stopped all sorts of speculations about the incident being made including the men being affiliated with Iran or, as Secretary of State Rubio put it, “a foreign actor”, a training exercise, or some sort of cover-up. Perhaps the authorities are trying to prevent an overreaction.
The difficulty is that silence can have the opposite effect. Once officials publicly invoke terrorism but leave the central facts unexplained, the public may decide which rumors fill the gap. They may be trying to lower the temperature while inadvertently making speculation more attractive.
As Jonathan Swift put it nearly 300 years ago, a lie can get halfway around the world while the truth is putting its boots on.
There’s a couple of reasons I could think of why the police are being circumspect.
1. It was overhyped and there wasn’t actual malovolent intent.
2. The police don’t want to prejudice any future potential criminal prosecutions.
3. When you are talking about 5 men and 3 vans, as alleged, that’s a scale where the police would suspect support networks, unknown conspirators. Best not to tip your hand on what is known about them before that risk is minimized.