The Chief Constable has accused some Westminster politicians of failing to understand the dangers of a dissident republican threat in a post-Brexit north.
In an interview in the Sunday Times, PSNI chief George Hamilton warned the government is failing to prepare for the impact of leaving the EU with regards to peace and security.
He said some Westminster politicians view Northern Ireland as "peripheral".
"There's a feeling that as regards the Troubles and the conflict, Northern Ireland is sorted and we don't need to worry about it, when actually we're working flat out 24/7 to keep a lid on it," he said.
He said future physical infrastructure or border officials would become targets for dissident republicans and require police protection.
"The purpose for which those checking points and border controls would be put in place would become less and less relevant because they would move away from issues of trade or movement of people to old-fashioned security on a national frontier," he said.
"That was done during the period of the Troubles rather unsuccessfully, and was sadly the subject of attacks and many lives lost.
"I have a concern some may see issues to do with the Irish border as literally peripheral, not just geographically but in terms of impact."
