Detectives in Northern Ireland are questioning a 45-year-old man about the bomb attack in April outside Palace Barracks in Holywood.
A dissident republican group claimed responsibility for the explosion at the base, which houses MI5’s Northern Ireland headquarters.
The blast happened minutes after policing and justice powers were devolved from Westminster to Stormont.
The PSNI arrested the man in north Belfast this morning and brought him to Antrim police station for questioning.
A number of arrests have been made concerning the attack but so far, no-one has been charged.
