Downing Street has insisted RAF Fairford is safe after the US withdrew its bombers from the base over new security concerns.
However, ITV News has now learnt from a source familiar to the investigation that Washington was concerned about the potential for a multiple drone attack on the site.
President Donald Trump has also said that "there were some threats" that led to the aircraft being moved.
The Pentagon confirmed on Sunday that aircraft which were being stationed at the Gloucestershire base had been “redeployed to their home stations in the United States”.
The move follows the arrest of six individuals over the past week in connection with a suspected terror plot targeting the base, which is used by the United States military.
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