The Government has declared it is demanding "special status" for Northern Ireland after Brexit.
Foreign Affairs Minister Simon Coveney has dismissed "language coming from London" in recent days that technology alone - cameras and online permits - could bypass the need for border posts on the island of Ireland.
Mr Coveney, who met with EU chief Brexit negotiator Michel Barnier during the week, said an unprecedented "political solution" was needed to keep the status quo and an effectively invisible frontier.
"What we are insisting on achieving is a special status for Northern Ireland that allows the interaction on this island, as is currently the case, to be maintained," he said.
"It is not so much about a soft or hard border, it is about an invisible border effectively, that you don't notice as you cross it.
"To achieve that, we need to draw up a political solution here as well as technical and practical one, which doesn't really have any precedent in the European Union."
Mr Coveney said the solution would have to respect the territorial integrity of Northern Ireland within the United Kingdom.
It would also have to make sure it did not create a back door to entering the European single market, he added.
"This is not going to be a straightforward problem to solve," he said.
The call for "special status" is a departure for the Government. It was immediately welcomed by Sinn Féin senator Niall O Donnghaile as a "significant" shift.
Unionists have argued against special status for Northern Ireland within the EU, claiming it is being planned as a back door to a united Ireland.