British police said a 27-year-old British-Iranian dual national was arrested Thursday. A widening counter-terror investigation linked to a suspected plot targeting RAF Fairford has led to a sixth arrest, as detectives pursue what they describe as a complex case with potential international dimensions. Key points and original sources are listed below.

• British police said a 27-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.S1

• A widening counter-terror investigation linked to a suspected plot targeting RAF Fairford has led to a sixth arrest, as detectives pursue what they describe as a complex case with potential international dimensions. Counter Terrorism Policing (CTP) said a 27-y...S2

• The 27-year-old was arrested in London on suspicion of plotting a terror attack following a security incident at RAF Fairford on the weekendS3

• The 27-year-old man was arrested in London on Thursday, and police have searched two properties in the UK capital.S4

• British police have arrested a dual UK-Iranian national on suspicion of plotting a terror attack following a security incident at a U.S.-run air base on the weekend.S5