What will happen to the Irish border after Brexit, when is the deadline for EU negotiations and what currently happens at the crossing?
THERESA May's hopes of getting a Brexit deal through Parliament could depend on the Irish "backstop" agreement she makes with the EU.
The backstop is effectively an insurance arrangement to ensure the border remains open if no wider deal is agreed on future UK/EU trade. Here's how negotiations have played out.
What is the Irish border problem?
Currently the border between Northern Ireland and the Republic is open with no checks on goods or people.
Ireland and the UK are in a "common travel area" of passport-free movement.
And as they are both in the EU single market, there is no restriction on goods and no tariffs.
Leaders in London, Belfast, Dublin and Brussels are keen to avoid a "hard border" after Brexit — when the UK has vowed to leave the single market and customs union.
This would mean border checks being reintroduced to monitor movement between jurisdictions operating under the two different regulatory systems.
There were fears this could have jeopardised the Good Friday Agreement peace deal.
Irish PM Leo Varadkar said he could block Brexit talks unless the UK signed a formal agreement not to have a hard border.
If this happened Ireland’s businesses could be left paying tariffs on imports and exports with its biggest single trading partner, Britain.
Some had suggested moving border checks across the Irish Sea — but Unionists and Brexiteers rejected that, saying it undermines the integrity of the UK.
World Trade Organisation (WTO) spokesman Keith Rockwell said: "There is nothing in WTO rules that forces anyone to put up border posts.
"Someone has to bring a complaint and say that their interests have been hurt.”
What have MPs said about a hard border?
It has been reported that the EU is preparing to accept use of technology to avoid the need for new border infrastructure.
EU negotiator Michel Barnier is working on a plan to use technology to minimise border checks in a major boost to Theresa May’s chances of clinching a deal.
Boris Johnson, former Foreign Secretary claimed, the Prime Minister's disastrous Brexit plans could lead to a "spectacular political car crash".
Northern Irleand's Democratic Unionists Party's ten MPs have pledged to oppose the deal.
In an interview with the BBC, Mrs Foster said: "The disappointing thing for me is that the prime minister has given up and she is saying this is where we are and we just have to accept it.
"She may have given up on further negotiations and trying to find a better deal but I have not given up.
"I believe in a better way forward and I believe we must find that."
Troops could return to the Northern Ireland border if there was a No Deal Brexit, the Irish PM warned.
And Leo Varadkar said the posting of soldiers there could spark a return to violence as the army would once again "become targets".
He told Bloomberg that a worst-case scenario could "involve people in uniform and it may involve the need, for example, for cameras, physical infrastructure, possibly a police presence, or an army presence to back it up."
And he added, in a stark hint that the situation could return to violence: "The problem with that in the context of Irish politics and history is those things become targets."
The Northern Irish backstop was the way to avoid this, he insisted, and even said his country was being "victimised" by Brexit and they WERE prepared to compromise.
"We're the ones already giving," he claimed at the World Economic Forum.
An Irish Government spokesman later clarified the PM was talking about how the border used to be during the Troubles.
He said: "He was not referring to Irish personnel and the Irish government has no plans to deploy infrastructure or personnel at the border."
The dire warning will severely undermine his hardline stance on the backstop at a time when the EU's position on the border is in disarray.
Brexiteers have warned Theresa May the only way to save her deal is to ditch the hated Northern Irish backstop as they team up with Remainers MPs today to find a solution.
The PM has summoned a group of top Tories to knuckle down this week and figure out how to persuade the EU to give us a different system for the Irish border.
They will discuss a compromise proposal created by a cross-Brexit group last week which would involve extending our transition period for a year to get a trade deal, and would rip up the current backstop arrangement.
MPs include Brexiteers Marcus Fysh and Owen Paterson, with Remainers Damian Green and Nicky Morgan. They will meet with Brexit Secretary Steve Baker later today.
Mr Fysh told the BBC this morning that the ideas were brand new, saying: "These are proposals that have not been discussed in the negotiations yet."
Talks will go on into Tuesday and Wednesday too in a hope they will figure out a detailed solution to break the deadlock as soon as possible.
Time is running out as the clock runs down to March 29.
What happens at the border at the moment?
The international border between Northern Ireland and the Republic of Ireland is about 310 miles long with, depending on how many tracks you include, as many as 275 crossing points.
In reality, the entire border is a crossing point because, apart from road signs changing from miles per hour to kilometres per hour, there is no physical infrastructure to see where the countries change over.
Following the 1998 Good Friday Agreement, which was the basic building block of peace in Northern Ireland, security checkpoints were removed from the border making it all but invisible.
How have the Brexit negotiations over Ireland unfolded?
The other 27 EU states have signed off the first phase of talks before negotiations now move on to trade and the future relationship - which also has to be signed off by the EU 27 and the European Parliament.
A deal to break the Brexit deadlock looked set to go through after Britain agreed to a reported £44bn divorce bill and a fudge on the jurisdiction of European judges.
The final sticking point - on the Irish border - meant the deal collapsed, leaving Theresa May in a race against time to get agreement before a crunch EU summit towards the end of 2017.
A leaked draft appeared to show the UK had vowed to ensure "continued regulatory alignment" with the EU so as not to undermine the Good Friday Agreement.
This likely meant both sides would follow the same rules governing trade to ensure goods can continue to move freely across a "soft" border with no checks.
The agreement has been dubbed the backstop arrangement.
Theresa May and Jean-Claude Juncker announced a breakthrough in talks on December 8, 2017, including an agreement on the border issue.
Arlene Foster, the leader of the DUP backed down after slamming the previous agreement, saying “substantial changes” to the text rejected would mean there was “no red line down the Irish Sea”.
In July 2018 Mr Varadakar said the EU had promised him no physical checks will need to be erected on the Irish border even if the UK crashes out with no deal, although this claim was disputed.
Also in the same month the EU's chief negotiator Michel Barnier issued the UK a 13-week deadline to solve the issue of the Irish border.
Mrs May used a column in German newspaper Die Welt in September 2018 to call on EU leaders to work with Britain to come to a deal.
She wrote: "Neither side can demand the unacceptable of the other, such as an external customs border between different parts of the United Kingdom."
Chief EU negotiator Michel Barnier said that the EU is ready to adapt its proposal on the Irish border in order to "de-dramatize" the issue.
He said the EU is not proposing "a border, neither on land or at sea.
"No. It is a set of technical controls and checks, a lot of which, most, can be put in place and carried out in places other than physically in Northern Ireland."
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On October 15, it was reported DUP Leader Arlene Foster believes the UK is set to leave the EU without a deal at all.
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On January 29, May urged MPs to give her "the clearest possible mandate" to go back to Brussels and reopen Brexit negotiations with the aim of replacing the controversial backstop.
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