Boris Johnson became prime minister two years ago this week and later won an election promising to “get Brexit done”. On Wednesday his minister in charge of EU relations, David Frost, set out plans to rework a central part of the withdrawal agreement the pair negotiated and agreed with Brussels. “The difficulties we have in operating the Northern Ireland protocol are now the main obstacle” to a good relationship with the EU, Frost told the House of Lords. He regretted that the relationship was “punctuated with legal challenges” and “characterised by disagreement and mistrust”. An easier relationship brimming with goodwill between the two parties is unlikely to materialise anytime soon, and Frost’s statement explains why. EU officials are exasperated by government claims not to have foreseen the changes to trade between Britain and Northern Ireland. Over 31 pages of annexes, the protocol Frost and Johnson negotiated lists every EU law that applies in Northern Ireland, including customs and animal health checks. Brussels is also fed up with what it sees as a refusal to acknowledge the EU’s efforts to soften the protocol, such as an extended grace period to allow chilled meats to continue to move between Great Britain and Northern Ireland and a promise to rewrite EU law on medicines. The two sides also sparred over Gibraltar this week, when the UK’s foreign secretary, Dominic Raab, criticised an EU proposal for negotiating a new deal over movement of goods and people on the territory. Against that unpromising backdrop, Frost’s demands to rewrite the Northern Ireland protocol hit a brick wall and the EU immediately ruled out any renegotiation. Many of the government’s latest ideas have been floated and shot down before. A trusted trader scheme that would rely on UK lorry drivers being honest about the destination of their goods is a rehash of “alternative arrangements” promoted by Tory backbenchers during the parliamentary Brexit wars. Such ideas were rejected because the EU single market operates on rules, not trust. Tensions will simmer during a summer of technical talks, but they are unlikely to reach boiling point until the autumn. The truce on chilled meats set to expire on 30 September. If the government fails to renegotiate the protocol, it says it is prepared to escalate the fight. Frost has threatened to trigger article 16, an emergency brake that allows either side to suspend parts of the protocol that lead to “leads to serious economic, societal or environmental difficulties … or to diversion of trade”. For now the government prefers to keep talking. It wants to keep the threat on the table, but triggering article 16would be a high-risk gamble because the EU would hit back with retaliatory tariffs, sending relations into a downward spiral. If that situation were to arise, the government has already made it clear who it thinks would be to blame. In an unusual score-settling exercise, the command paper published on Wednesday argues that Frost’s negotiators had little choice but to accept the Northern Ireland protocol. Blame is shared out between Theresa May, rebel MPs and the EU but not Johnson, who promised there would be no checks between Britain and Northern Ireland.