The UK will lay out its plan to amend its post-Brexit trade deal Tuesday in a direct challenge to the European Union, which is insisting that Prime Minister Boris Johnson must honor the agreement he signed.

Foreign Secretary Liz Truss will make a statement in the House of Commons, setting out her plan to introduce laws that would override parts of the Northern Ireland protocol if negotiations fail to make headway after months of stalemate with the EU. Johnson said late Monday that he’s prepared to unilaterally amend the agreement over Northern Ireland, though would prefer a negotiated solution.

Tensions have flared between the two sides in recent weeks over the UK’s repeated threats to renege on its obligations to make checks on some goods entering Northern Ireland in order to protect the EU single market without creating a hard border on the frontier with the Republic of Ireland.

The British government is frustrated that the deal has created a customs border with the rest of the UK, disrupting trade and contributing to the collapse of the executive in the region. The EU is ready to suspend the entire trade agreement if Johnson makes good on his threats.

The renewed threat of a no deal comes as the UK economy is facing an already dire outlook thanks to soaring inflation and a deepening cost of living crisis. The Bank of England said this month it expects a sharp downturn at the end of this year, and almost no growth at all in 2023 and 2024.

A further hit could tip the economy into a full blown recession. Back in 2020, Bloomberg Economics forecast the impacts of tariffs that would apply without a trade deal with the EU would knock at least 1.5 percentage points off growth the next year.

While Truss may not start the legislative process straight away, simply laying out the plans will be seen as a provocative move by the EU. The tone of her statement will be carefully observed in Brussels, with Truss tending to use tougher language than Johnson in recent weeks.

“We would love this to be done in a consensual way with our friends and partners, ironing out the problems, stopping some of these barriers East-West,” the prime minister said in a pooled TV clip from Belfast on Monday. “To get that done, to have the insurance, we need to proceed with a legislative solution at the same time.”

A serious dispute between the UK and the EU would be an unwanted problem for US President Joe Biden as he seeks to maintain the pressure on Russia over the invasion of Ukraine. The UK, the EU and the US have largely managed to coordinate their efforts to sanction Russia and provide weapons and financial support to the Ukrainian government. Ireland’s Foreign Minister Simon Coveney hinted at the risks to the war effort late Monday.

“This is not a time for unilateral action announcing legislation which would essentially breach international law, undermine an international treaty and create a lot of unnecessary tension between Brussels and London,” he said.

Truss had calls with US House Speaker Nancy Pelosi and EU negotiator Maros Sefcovic on Monday and reiterated Britain’s commitment to the Good Friday Agreement—the 1998 peace deal which drew a line under decades of violence in the region—and getting the Northern Ireland executive up and running. The US has consistently urged the UK to cooperate with the EU over the issue and warned against unilateral action.

Truss’s plans are expected to deal with customs delays by creating separate lanes for goods going to either Northern Ireland or the Republic of Ireland, the Sunday Times reported last weekend. She may also allow firms to produce goods to UK standards in Northern Ireland, put governance of the border in the hands of UK courts rather than the European Court of Justice and give the UK the right to change tax rates in the region.

Johnson is also trying to coax Northern Ireland’s unionist parties into forming a new power-sharing executive with the winners of this month’s elections, Sinn Fein. Johnson spoke to the leaders of the different political parties on Monday and said none of them like how the protocol is operating.

“They all think it can be reformed and improved, from Sinn Fein to the SDLP to the DUP, all of them,” Johnson said. But when asked whether he’d appealed to the DUP to join the new administration with the Sinn Fein, and whether such a government was more likely to be formed following his outreach, he said “you bet.”

“Everybody should be rolling up their sleeves and getting stuck in to the government of Northern Ireland,” he said.