A photo of Ann Widdecombe, a former Conservative lawmaker who became a spokeswoman for the Reform U.K. party, during a party conference in Birmingham, England, last month where Nigel Farage spoke.
Economies in Latin America and Europe rely on American diesel. Stopping exports could tip some countries into recession, hurting trade with the United States.
British police said a 25-year-old British-Iranian dual national was arrested Thursday. British officials have said they believe Iran played a part in planning the incident at R.A.F. Fairford.
The French government soured on a reciprocal deal that allowed the British authorities to return some migrants who crossed the English Channel illegally in small boats.
The British prime minister, Andy Burnham, said there were “strong indications” Iran played a part in the events at R.A.F. Fairford on Sunday, without providing details why.
Outside the R.A.F. Fairford base in southwest England on Monday. Mr. Burnham said there was an “ongoing, complex and serious police investigation,” and that Britain was working closely with the United States.
The prospect of an attack on an air base used by U.S. forces prompted stepped-up protections across Europe, but confusion shrouds the case, in which the suspects were released on bail.
A police officer at a roadblock near R.A.F. Fairford air base, possibly the target of an attack plot, in Fairford, Gloucestershire, England, on Tuesday.