The new document Boris Johnson sent to the European Commission president proposes a radical overhaul of the Brexit divorce agreement negotiated by Theresa May's government. It has been welcomed by the EU as a positive step — but leaders have been quick to highlight problems.
The biggest difference is that the controversial Irish backstop — to guarantee an open border between Northern Ireland and the Republic of Ireland — is scrapped.
The backstop — contained in the Withdrawal Agreement negotiated by the May government but rejected by the British parliament — would keep the UK in a temporary customs union, if no free trade deal or alternative plan had been agreed by the end of a post-Brexit transition period.
Here is a look at some of the main proposals in the UK plan — and why they risk causing a headache for the European Union.
Customs union: Northern Ireland to leave
The UK wants to leave the EU’s customs union in 2021, after a planned transition period, to pursue an independent trade policy. The plan makes it clear that Northern Ireland, as an integral part of the UK, would leave too.
Boris Johnson acknowledges that this means checks would be inevitable, but insists they would not jeopardise the open border between north and south. The EU opposes customs checks on the island of Ireland, which Brussels and Dublin say risk disrupting the all-island economy and may pose a threat to peace.
The prime minister says there would be “no new physical infrastructure” at the border. The EU has always been sceptical about this. It argues that no other customs border in the world is check-free, and fears that a porous frontier would be a smugglers’ charter.
To deal with tariffs and rules of origin, the UK proposes trusted trader schemes and simplified procedures. Checks would be minimal and take place away from the border at business premises or at “other designated locations”. The plan relies heavily on technology such as satellite tracking.
The EU has repeatedly rejected such “alternative arrangements” put forward by Eurosceptics, arguing that the technology either does not exist or is untested — and in any case would not provide an equivalent cast-iron guarantee to the backstop.
The Johnson plan demands exemptions for smaller businesses, which may require the EU to change its customs rules.
Single market: Northern Ireland to remain (partially)
Boris Johnson’s plan envisages Northern Ireland staying subject to EU single market rules for agriculture, food and manufactured goods. This would mean a new regulatory border in the Irish Sea, with checks on items coming from Britain. Such checks already happen with animals.
This goes further than his original proposal, which was for regulatory alignment with the EU only on agri-food standards. It has been welcomed by EU officials.
Consent: Northern Ireland to decide
However, the single market arrangements would have to be reviewed by Belfast. The Northern Ireland Executive and Assembly would then have to decide every four years whether to continue following EU rules, or opt into British regulations.
The EU’s fear is that if Stormont chose the latter course, this would bring a hard border as new customs and regulatory checks would be needed.
The plan also poses a political problem, given the delicate balance between nationalists and unionists in Northern Ireland’s power-sharing arrangements. Dublin fears that it would hand the hardline Democratic Unionist Party (DUP) an effective veto.
Also, doubt is cast on the proposal by the fact that the Stormont assembly has not sat since early 2017 due to political deadlock.
Can the Johnson plan survive?
EU officials are relieved that the UK prime minister has not presented the plan as a “take it or leave it” offer, as Downing Street had threatened he would.
Brussels sees it as a starting point for further negotiation, even though Boris Johnson has said the only alternative is “no deal” and the obstacles to overcome are formidable.
The British government has called on the European Union to compromise. But the EU says London’s proposals must be realistic and legally enforceable.
Politics will undoubtedly come into play. The EU does not want a no-deal Brexit, and certainly does not want to be seen as being responsible for such a scenario.
However, its credibility especially with smaller states would be hugely damaged if it sacrificed Irish concerns to bend the rules and secure a deal with the UK.
The EU's priority is to preserve its cohesion, along with the integrity of its single market, institutions and founding principles — as well as upholding peace and security on the island of Ireland as set out in the Good Friday Agreement.