In choosing his own hardline Brexit strategy, newly-installed British prime minister Boris Johnson has left Taoiseach Leo Varadkar in no doubt about his own next steps.

Johnson is not looking for changes to the backstop, he is looking for it to be dumped completely. By choosing the path he has, it means that Varadkar’s only job now is to defend the backstop.

Johnson’s demand that the abolition of the backstop, the insurance policy to avoid a hard border, is a prerequisite for a Brexit deal is an impossible one, and the new British prime minister knows this.

In recent weeks, Stephen Barclay, reappointed as Brexit secretary by Johnson, was told in Brussels that Ireland and the European Union could not, and would not give way.

The EU’s chief Brexit negotiator, Michel Barnier – who Brussels sources predict will remain in place for another two years and oversee the future EU-UK trade talks – yesterday said Johnson’s demands are “unacceptable”.

“A time limit is not enough,” Johnson told the House of Commons, shooting down one potential area of compromise on the backstop, even if it has never been seen as a viable option in Dublin.

Bit by bit, he sought to demolish all Dublin believes the backstop achieves, and to see off any avenues of retaining an amended version of it. Instead of resisting pressure to amend or tweak it, Varadkar’s task now is simply to defend it.

Issues around the Border, Johnson said, should be “dealt with where they should always have been: in the negotiations on the future agreement between the UK and the EU”.

From the Irish Government’s perspective, the backstop’s purpose is to avoid the Border being used as a pawn in later negotiations between London and the EU27 on a future EU-UK trade deal.

That was the central purpose of the initial deal struck in late 2017, which Johnson described as “the very trap from which it is now absolutely vital that we escape”.

Technology

“We believe – and it is common ground in Dublin, Brussels and elsewhere – that there are facilitations available to enable frictionless trade not just at the Northern Irish Border but at other borders too,” Johnson added falsely.

No one in the circles that count in Dublin and Brussels believe that such technology exists.

Varadkar has raised the prospect of the backstop applying only to Northern Ireland, as had originally been intended, rather than keeping the entire UK in a customs union with the EU. But Johnson struck this out, too.

“I do not accept the argument that says that these issues can be solved only by all or part of the UK remaining in the customs union or in the single market.”

Such impossible demands set the UK towards a crash-out Brexit at the end of October, unless Johnson opts first for a general election or a second referendum if he is frustrated by MPs.

They are also likely to relegate economic concerns in the backstop debate. The idea gaining ground in London that Dublin, faced with the economic cost of no deal, would buckle arguably applied only if the UK requests were reasonable.

Johnson’s are not, and the EU is unlikely to give an inch even if Ireland wanted to do so.

Yet, for Dublin, economics was always secondary to the argument that the backstop is needed to protect the Belfast Agreement.

“There are some things that are more important than economic relationships, and this is one of them,” Tánaiste Simon Coveney said in January.

Johnson’s approach makes compromise almost impossible. An extremely fraught period in British-Irish relations lies ahead.