The PSNI Chief Constable is to call for the government to provide millions in funding for additional officers to handle border security after Brexit.
George Hamilton is drawing up a professional business case for an uplift in numbers to present to Government.
Speaking at the Police Federation annual conference, he described the move as "sensible planning".
"All we are doing is saying let's do some sensible planning that will enable us to match fit, to be ready for the post-Brexit era," he said.
"And if we end up with some sort of an agreement that doesn't require these additional officers we can very quickly recalibrate downwards and that will be the thrust of the business case we present to government."
He would not be drawn on the numbers involved.
All sides in the Brexit negotiations are keen to avoid a return to the heavily-militarised checkpoints of the past. The frontier is one of the most vexed issues facing the EU and UK talks teams.
Mr Hamilton said analytical work by experts was continuing to help the force build a business case but noted significant uplifts in staffing numbers in partner organisations HMRC and Border Force.
The Police Federation said at least 300 officers would need to be redeployed to effectively police a soft Irish border.
Federation chairman Mark Lindsay said: “In effectively policing a soft border, there is the requirement for at least 300 officers to be redeployed.
“Quite simply, these are officers we do not have at present.”
If we were stretched in the 70s, 80s and 90s, is it not fair to say that we will be well and truly incapable of performing the task with officer numbers of 6,621 or a sixth of what we had then?Chairman Mark Lindsay
Mr Lindsay added: “Additional real estate will need to be retained and we have already seen the sale of Warrenpoint PSNI station halted.
“I would anticipate that stations previously earmarked for closure will now need to be retained.
“In order to protect officers, there is an expectation that additional armoured vehicles will be required. Not inexpensive on their own.”
He said when the currently shrunken force, in line with peacetime requirements recommended by an independent report, had 13,500 officers, supported by 26,000 soldiers, it proved a daily challenge to police the Troubles border.
“So, if we were stretched in the 70s, 80s and 90s, is it not fair to say that we will be well and truly incapable of performing the task with officer numbers of 6,621 or a sixth of what we had then?
“There is a time to get real around all of this, and that time is now.”
We don’t possess the numbers, the security apparatus or specialist resources for increased counter terrorist, search and support duties along the borderChairman Mark Lindsay
He said he anticipates considerable extra legal costs will be required in extradition cases and called for adequate funding.
“We don’t possess the numbers, the security apparatus or specialist resources for increased counter-terrorist, search and support duties along the border.”
The chief constable said if there was an increased footprint for HMRC, Border Force and the Environment Agency to deal with compliance issues then the nature of the operating environment would require deployment of officers to ensure the safety of officials.
“I am pretty sure it will require an uplift and there will be a strong evidence base for that.”
He added: “I am building the evidence base to make it a credible and professional business case.”