A 21-year-old man has been arrested on suspicion of the possession of documents likely to be useful to a terrorist.
The arrest in York was part of a planned operation by Counter Terrorism Policing North East.
A bomb disposal unit was called during a search of a property in the Boroughbridge Road area in the city, officers said.
A number of residents were evacuated for a short period.
The arrested man remains in custody, while roads in the area have reopened and a cordon has been lifted.