Brexit position papers to be released this week risk fuelling tension between Dublin and London.
Taoiseach Leo Varadkar wants British Prime Minister Theresa May to avoid border checks.
But British cabinet ministers Philip Hammond and Liam Fox have clearly indicated the UK's intention to ignore that plea.
The UK government believes a "light touch border", using some checks and new technology, will solve the problem.
Speaking back in July, Mr Varadkar said leaving the European Union was not an Irish policy and it was not up to Ireland to design the solution to Britain's departure.
"It's as simple as this: between Ireland and Northern Ireland there is a political border. Northern Ireland is part of the United Kingdom, Ireland is a sovereign, independent state.
"But currently there is no economic border and there hasn't been an economic border since 1992 - and as far as this Government is concerned there shouldn't be an economic border, we don't want one.
"It's the United Kingdom, it's Britain that has decided to leave; and if they want to put forward solutions - smart solutions, technological solutions, borders of the future and all of that - that's up to them.
"We're not going to be doing that work for them, because we don't think there should be an economic border at all".
"We're not going to be helping them to design some sort of border that we don't believe should exist in the first place.
"So let them put forward their proposals as to how they think a border should operate, and then we'll ask them if they really think this is such a good idea because I think it'll have a very severe impact on their economy if they decide to go down that route".
In fields which straddle the Irish border, they risk having some animals in the EU and others outside it.
Fermanagh farmer John Sheridan says Mrs May's proposals amount to "a hard border by stealth".
"We have got rid of that for the last 20 years so to bring that back, you're just putting a sledgehammer in the centre of a community," he argued.
Some people living on either side have placed cushions on the bridge, literally "softening the border" in protest at any plans for customs posts.
Visual artist Rita Duffy explained: "It cannot be secured, tightened or, as Donald Trump would suggest, walls built.
"When you're standing in the beautiful landscape, wild and free, and then you think hard border? It simply can't be allowed to happen."
Border checks are not optional for a country outside the customs union. They are required under EU law.
So authorities will have to find a way to monitor the 310-mile long border and its network of up to 200 invisible crossing points.
Former Northern Ireland secretary Owen Patterson believes the British government's proposals are workable.
"In all the time I've been going to Northern Ireland... nobody has ever mentioned this as a problem," he said.
"So I honesty think with modern technology, modern invoicing, this is all easily surmountable."