Pensioners in their eighties were forced to leave their homes in the middle of the night after a mortar-type device was left in a nearby graveyard.
Police evacuated residents after the weapon was discovered in Strabane, Co Tyrone, on Saturday evening.
A senior PSNI officer blamed those with an agenda of “violence and destruction” for the disruption.
Ulster Unionist Assembly member Ross Hussey said: “No doubt the people responsible would claim to be republicans fighting to ‘liberate’ Ireland.
“In reality they are a criminal gang of bully boys and fascists whose only achievement this weekend was to force local people, some in their eighties, to leave their homes in the middle of the night and seek refuge in church halls or with friends and relatives.”
The police operation began in the early hours of Saturday after reports that a device had been left in the Townsend Street/Cemetery Road area.
A number of elderly people had to leave their homes and the graveyard was closed for most of the day. It was later confirmed as a mortar-type device, police said.
Supt Mark McEwan said: “We would like to thank the local people who have been inconvenienced by this operation for their patience and understanding and we are working to get them back into their homes as soon as possible.”
Dissident republicans opposed to the peace process have killed police officers, soldiers and a prison warder in recent years.
The chairman of the Police Federation for Northern Ireland, Mark Lindsay, said: “As PFNI chairman, I wish to condemn the actions of misguided people who think that what they did in Strabane would serve to advance their aims. Such attempts at murder have never, and will never, progress any political objective.
“People want to get on with their lives without a threat to life or wholesale disruption to a community.”