Dissident republican bombers have struck twice in recent weeks.
On Saturday a bomb exploded at Dunmurry PSNI station in Belfast. 
The bombers used an almost identical method to those who tried to attack Lurgan police station last month.
In both attacks a delivery driver was hijacked, threatened, and told to drive the bomb to its target.
These attacks, claimed by the New IRA, came after a lull in violence– so what has sparked this outbreak? 
Ciarán Dunbar is joined by Belfast Telegraph security correspondent, Allison Morris.

The BelTel brings you some of Northern Ireland's top journalists, Allison Morris, Sam McBride and Suzanne Breen to name but a few, giving you the inside stories behind what is in the news. Presented by Ciarán Dunbar, the Bel Tel investigates, debates and informs every Monday, Wednesday and Friday.