The United Kingdom's post-Brexit strategy came under attack at home and abroad on Tuesday after the government admitted its planned legislation for Northern Ireland would "breach international law", superseding the provisions of the EU divorce deal.
It immediately raised questions concerning trust in Boris Johnson's administration, and followed the prime minister's threat earlier in the week to pull the UK out of talks on the future relationship.
Ireland's Foreign Minister Simon Coveney said the UK's approach was "hugely problematic and illegal". The European Parliament President David Sassoli warned that "trust and credibility" will be lost if the UK breaks its commitments.
Amid a torrent of criticism at home -- from among the ruling Conservative ranks as well as opposition figures -- Johnson's predecessor Theresa May questioned whether the UK would be trusted internationally if it broke its obligations under the divorce deal.
The Northern Ireland Protocol is part of the Withdrawal Agreement which has the force of an international treaty. The EU has warned that failure to respect its terms will jeopardise any post-Brexit agreement.
Opposition Labour leader Sir Keir Starmer wondered whether the UK plan was a negotiating tactic to obtain leverage in trade negotiations. Talks resumed on Tuesday in London in an attempt to break the stalemate.
The head of the European Council of EU leaders Charles Michel called for calm on Tuesday amid heightened tensions in the post-Brexit trade talks, while warning the UK that its decision to "leave the club" means "there are consequences".
Throwing his weight behind Michel Barnier, the former Belgian prime minister told Euronews that the bloc's chief negotiator had a "clear mandate" and defended the firm line taken by the EU over the UK's future access to EU markets.
Boris Johnson has threatened to walk out of the talks unless a deal is struck by mid-October. A transition period keeping most current arrangements in place expires on December 31.
Speaking to Euronews Political Editor Darren McCaffrey, Charles Michel refused to be drawn when asked whether the UK was still a reliable partner with a prime minister who could be trusted.
"Let’s keep cool, I know from my Belgian experience that each particular negotiation and especially Brexit is always a difficult process," he said. "We gave a clear mandate, we trust Michel Barnier and we will follow in next days and the next weeks the next steps."
Asked whether a deal was now more or less likely than before the summer, Michel would not make a prediction, saying the EU would "focus on the substance".
"Everyone understands the level playing field is a top priority for the European Union, for obvious and very legitimate reasons, and everybody can understand if you take the decision and it is your right to leave the club there are consequences," the European Council President said.
The President of the European Parliament, David Sassoli, later added his voice, saying he was "worried by the lack of progress" in the talks and warning the UK to "honour the commitments that it signed up to last year".
'More realism' needed from EU
The UK and the EU have been at loggerheads in the trade talks over future competition, particularly rules on state aid, and fishing rights.
The European Union needs to be "more realistic about the UK's status as an independent country" in talks over its future relationship with Europe, Britain's Brexit negotiator David Frost said earlier on Tuesday. He called for "progress" ahead of the resumption of talks with Barnier.
“We have now been talking for six months and can no longer afford to go over well-trodden ground. We need to see more realism from the EU about our status as an independent country."
Frost said the UK had listened carefully to the UK and proved itself flexible in negotiations, and if the EU could not move forward then Britain was preparing for a no-deal exit when the transition period ends on December 31.
“If they can’t do that in the very limited time we have left, then we will be trading on terms like those the EU has with Australia, and we are ramping up our preparations for the end of the year.
Trade deal 'still possible'
Meanwhile, the German government said on Monday a Brexit deal between the UK and the European Union was still possible and that it’s in the interest of both sides to secure one.
“Britain in particular needs to move on the core issues of governance, what’s summed up as ‘level playing field,’ and on the issue of fisheries,” said German government spokesman Steffen Seibert during a news conference in Berlin.
"The German government continues to be convinced that it's still possible and also that it's in the interest of both sides to reach such an agreement (on Brexit), but of course one needs to reach an agreement with the United Kingdom as quickly as possible," he added, saying Germany fully backed Barnier's efforts on behalf of all 27 EU countries.
During the transition period, the UK remains within the EU’s economic orbit, benefiting from frictionless and tariff-free trade.
If the UK walks away from the talks or if the process collapses, the two sides would be heading toward a no-deal outcome that would see tariffs and other impediments to trade imposed at the start of next year.
UK warned over Northern Ireland plan
In the House of Commons on Tuesday, former British Prime Minister Theresa May took the government to task over its stance on Northern Ireland, amid reports it was planning to renege on the UK's commitments.
The Northern Ireland Protocol negotiated by Boris Johnson's government with the EU is part of the Withdrawal Agreement which has the force of an international treaty.
May reminded MPs that the UK government had signed the agreement and the protocol, and the British parliament had voted the deal into UK law.
"The government is now changing the operation of that agreement. Given that, how can the government reassure future international partners that the UK can be trusted to abide by the legal obligations of the agreements it signs?" she asked.
Brexit deal 'not like any other treaty'
The Northern Ireland Secretary replied that the British government had worked "in a spirit of good faith" with the EU "to ensure that we do implement the arrangements that uphold the fundamental principles that lie behind the Protocol".
"But the Withdrawal Agreement and Protocol are not like any other treaty. It was written on the assumption that subsequent agreements could be reached between us and the EU on the detail," Brandon Lewis said, adding that the government had a duty to provide certainty for businesses in Northern Ireland.
Responding to another question, the minister admitted that the government's bill on Northern Ireland, due to be published on Wednesday, "does break international law".
The protocol keeps Northern Ireland within the EU's remit to a certain extent from 2021, creating a regulatory filter between the territory and Britain. The UK government has repeatedly underlined the part of the accord which guarantees that Northern Ireland will have "unfettered access" to the UK's internal market.
The EU warned the United Kingdom on Monday that any attempt to row back on its Brexit commitments could jeopardise a future trade agreement and put at risk hard-won peace on the island of Ireland.
European Commission President Ursula von der Leyen said in a tweet that implementing the Withdrawal Agreement was "an obligation under international law and a prerequisite for any future partnership".