If the British government, at the behest of right wingers in the Tory Party and the Democratic Unionist Party (DUP), seek to restore the hard border in Northern Ireland, the Irish government has a clear duty to say no, loudly and firmly.
The Irish government must inform the European Union that they are vetoing the continuation of the talks between the EU and Britain, which they have a right to under the rules laid down.
But they also need to make it clear that they will not in any way assist or have any hand, act or part in the creation of a new border.
It takes two to create a borderline and police it effectively. If the Irish government makes clear that it will not administer the border then it becomes irrelevant.
In addition, there should be mass peaceful mobilization by the people of Ireland who know the reinstatement of a physical border will cause massive security and economic problems. The PSNI, the Northern police force, has already said patrolling the border and installing fixed security checkpoints will make their men and women sitting ducks for extremists hoping to reignite the war.
Brexit is the most important question facing an Irish leader in decades, probably since Albert Reynolds made the decision to throw the weight of the Irish government behind the then long shot peace process.
Current Taoiseach Leo Varadkar has a stellar resume, political smarts and an excellent grasp of the realities, but he will come under fierce pressure to allow EU/Britain negotiations to go ahead even if the Irish border issue is not resolved.
It would be disastrous to give in to such pressure. The worst of all solutions, something drafted in the final document which seeks to fudge the issue, would only make matters worse. Already the colonial grandees the Tory backbenches are calling for the hard border if that is what unionism wants.
Read more: What next for Brexit and Ireland’s border?
It is dangerous talk and confirms a mindset that remains as irresolute and imperialist as generations before them. The entire Brexit issue is a tribute to their utter political arrogance.
British Prime Minister Theresa May is an unbelievably weak figure, a woman who did not square away DUP support before signing off on what was a perfectly acceptable deal on Monday. Did she seriously think the toys would stay in the pram once the DUP saw the deal?
But even with that, May could have called the DUP bluff and dared them to bring down the government by withdrawing their support. A general election would see them lose access to power and, worst of all for them, might result in the election of Labour Party leader Jeremy Corbyn, an avowed supporter of a united Ireland and the unionists’ worst nightmare.
But May lacked the steel to go down that route and instead took part in a chaotic rowing back process that only undermined her position even more.
The fact is that it is the Irish who hold the high cards and the moral ground on this issue. They have stated plainly there can be no return to a hard border. That must stay the mantra despite EU and British pressure to think and act otherwise.
In the end, there is only one Brexit exit for Ireland on the border issue, and that is to have no physical border at all.