The P.S.N.I. believe dissident republicans were responsible for leaving a mortar bomb at the side of an N.I. road.
A horizontal mortar tube and command wire were recovered during a security alert on Drumnaquoile Road, Castlewellan.
The items were discovered a member of the public just before 3:00pm on Monday.
Detective Inspector Orr of Crime Operations Terrorism Investigation Unit said said it was too early in the investigation to say who was definitively responsible but said he suspected dissident republicans were involved.
"We implemented a full and extensive clearance operation in the area following the discovery yesterday afternoon. That operation concluded this afternoon and thankfully nothing further has been found.
"The mortar tube and command wire will now be subject to detailed forensic examination however our initial assessment is the items, which are in a fairly good condition relative to other similar devices we have uncovered, had not been at that location for very long and may even have been there for as little as one day."
Detective Inspector Orr added: "I am appealing for local people to help us identify those responsible for leaving this device so close to a public road and to come forward with any information they may have.
"Whilst at this stage, it is too early to attribute ownership to any particular grouping, it is my belief that dissident republican terrorists are responsible and that this find has undoubtedly prevented an attack on local police.
"We know that the vast majority of people support our police officers and simply want to live in a peaceful society. We will continue to work with communities to disrupt the activities of the small group of people who are intent on using violence. If you know anything that could help us, please call 101, quoting reference 721 08/04/19."