A man is being questioned by officers in the North investigating dissident republican activity.
The 36-year-old was arrested in Newry this morning and has been taken to the Serious Crime Suite at Musgrave Police Station.
A property was also searched as part of the crack down.
A 35-year-old man arrested in west Belfast yesterday has been released unconditionally.
While three other men, ranging in age from their 30s to their 40s, remain in custody.