What were the options for the Irish border agreed in the

Theresa May and the EU effectively fudged the Irish border issue in the Brexit divorce deal before Christmas.

But the commitments to leave the EU customs union, keep a soft border, and avoid divisions within the UK were always going to need reconciling at some stage. Currently 110million journeys take place across the border every year.

Both sides in the negotiations insist they want to avoid a hard border between Northern Ireland and the Republic, but their ideas for how the issues should be solved are very different.

If they fail to strike a deal it could mean a hard border on the island – which could potentially put the Good Friday Agreement at risk.

The agreement – struck in 1998 after years of tense negotiations and a series of failed ceasefires – brought to an end decades of the Troubles.

More than 3,500 people died in the ‘low level war’ that saw British Army checkpoints manning the border between Northern Ireland and Ireland. 

Both London and Dublin fear reinstalling a hard border – whether by checkpoints or other means – would raise tensions and provoke a renewal of extremism or even violence if people and goods were not able to freely cross.

The DUP – which opposed the Good Friday Agreement – is determined to maintain Northern Ireland inside the UK at all costs, while also insisting it wants an open border. 

The UK blueprint:

The PM has made clear her favoured outcome for Brexit is a deep free trade deal with the EU.

This would mean being aligned closely enough with the bloc that there is no need for customs checks.

Any remaining gaps in customs regulations as a would be covered with technological solutions.

That is likely to mean cameras and electronic records, which would arguably not constitute major physical infrastructure.

Boris Johnson has suggested that a slightly ‘harder’ border might be acceptable, as long as it was invisible and did not inhibit flow of people and goods.

However, Brussels has dismissed these ideas as ‘Narnia’ – insisting no-one has shown how they can work with the UK outside an EU customs union.

The EU blueprint:

The divorce deal set out a ‘fallback’ option under which the UK would maintain ‘full alignment’ with enough rules of the customs union and single market to prevent a hard border and protect the Good Friday Agreement.

The inclusion of this clause, at the demand of Ireland, almost wrecked the deal until Mrs May added a commitment that there would also be full alignment between Northern Ireland and the rest of the UK. 

But the EU has now translated this option into a legal text – and hardened it further to make clear Northern Ireland would be fully within the EU customs union.

Mrs May says no Prime Minister could ever agree to such terms, as they would undermine the constitutional integrity of the UK.

A hard border:

Neither side wants a hard border between Northern Ireland and the Republic. 

But they appear to be locked in a cyclical dispute, with each adamant the other’s solutions are impossible to accept.

If there is no deal and the UK and EU reverts to basic World Trade Organisation (WTO) relationship, theoretically there would need to be physical border posts with customs checks on vehicles and goods.

That could prove catastrophic for the Good Friday Agreement, with fears terrorists would resurface and the cycle of violence escalate.

Many Brexiteers have suggested Britain could simply refuse to erect a hard border – and dare the EU to put up their own fences.