A 28-year-old man has been arrested in connection with a mortar device found outside a police station in Strabane in September.
The man was arrested in the Strabane area on Wednesday morning under the Terrorism Act. A number of searches are ongoing in the area.
Police said the arrest and searches are linked to the discovery of the mortar device in the Church View area on September 7.
Detective Inspector Andrew Hamlin from the PSNI's Terrorism Investigation Unit said the device was "undoubtedly" designed to injure or murder police officers.
"It was recklessly left in a public area, just metres away from a number of family homes," he said.
“The New IRA were behind the attack and they demonstrated once again that they do not care who is hurt or killed by their violent actions. A number of small children were in close proximity to the deadly device and it is disgraceful that their lives were put at risk.
"A number of older and vulnerable people were also forced to leave the comfort and safety of their own homes."
He said that he believed those behind the attack were living in the local area.
“I believe that the New IRA members behind this attack are living in the community, amongst the people whose lives they put at risk. Our focus is on keeping the community safe and protecting them from the threat posed by these violent groups but we need the help of the public," Detective inspector Hamlin said.
"Our chances of success are vastly improved by support and information from community as today’s search and arrest operation demonstrates.
"I would strongly urge people to report any suspicions they have about dangerous and illegal activity in our community to police on 101 or alternatively, information can be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous.”