A farmer who called 999 when she saw a group of "masked men" near RAF Fairford in the early hours of Sunday believes she "foiled" their plans by "pure luck".

But she only has a "partial picture" of what happened, Defence Secretary Wes Streeting has said.

The RAF base is used by the US military, and President Donald Trump has stated that the US had the five men "under view for a long time".

So what really happened? BBC Security Correspondent Frank Gardner has this analysis.

More on the RAF Fairford incident.