The RUC is to bring extra resources, including the British army, into the area around Coleraine, Co Derry, following a series of pipebomb attacks.
A man escaped injury after a pipe-bomb was thrown through the window of a house in Portrush at midnight on Monday. The device did not explode and was made safe by the army.
There have been 11 pipebomb attacks in the Coleraine-Portrush area this year, and the RUC believes some of them might be linked.
In Ballymena, a car was damaged when a pipe-bomb exploded on the bonnet at about 1.40 a.m. yesterday.