The United Kingdom unveiled legislation to override parts of the Brexit deal it signed with the European Union, risking a trade war with the bloc and pitting Prime Minister Boris Johnson against opponents in his own fractured Conservative Party.

Boris Johnson

The bill seeks to hand the U.K. powers to unilaterally rewrite the bulk of the Northern Ireland protocol, which kept the region in the EU single market after Brexit, creating a customs border with mainland Great Britain. If passed, the new law would allow ministers to rip up the regulatory framework both sides agreed to in 2019 and replace it with new rules on customs checks, tax and arbitration.

“This is a reasonable, practical solution to the problems facing Northern Ireland,” Foreign Secretary Liz Truss said in a statement. “It will safeguard the EU Single Market and ensure there is no hard border on the island of Ireland.”

The move risks reopening divisions with the EU 2 1/2 years after the U.K. left the bloc, just as a unified approach to Russia following its invasion of Ukraine had bound them together again. It opens up Johnson’s administration to accusations that it’s breaking international law, and also threatens to deepen Tory splits over Europe just a week after the premier scraped through a confidence ballot that saw more than 40 percent of his MPs vote against him.

The Foreign Office said in its statement that the plans are “consistent with international law” and aimed at protecting the 1998 Good Friday peace deal in Northern Ireland.

But the legislation is expected to spark anger in Brussels where the European Commission may unfreeze infringement proceedings, which have been suspended during negotiations over how the protocol operates. That could ultimately lead to financial penalties being imposed on the U.K. The EU could also suspend its trade agreement with Britain, stop the privileged access U.K. companies have to the single market and halt talks over the status of Gibraltar, according to a person familiar with the matter.

The bill contains a provision for it to be replaced by a negotiated settlement, if one is agreed to with the EU. “In the meantime the serious situation in Northern Ireland means we cannot afford to allow the situation to drift,” Truss said.

Here’s what the bill aims to do:

• Introduce green and red trade channels, separating goods just flowing between Britain and Northern Ireland from goods intended for the E.U.

• Allow businesses in Northern Ireland to choose whether they follow U.K or EU standards, or both, for goods.

• Extend U.K. subsidy controls and tax breaks, including changes to value-added tax to Northern Ireland.

• Strip the European Court of Justice of its role in settling disputes over the Brexit deal in the region, allowing instead an independent arbitration panel to oversee legal issues.

Johnson’s administration argues that the present deal threatens the peace agreement because the Democratic Unionist Party is refusing to participate in Northern Ireland’s power-sharing executive until the protocol is changed, effectively blocking the formation of a new regional government.

But even before the government set out its plans, senior DUP MP Sammy Wilson told Bloomberg that the bill won’t be enough to spur his party to join a new regional government. Without DUP participation, a new executive can’t be formed.

Truss outlined her plan to publish the legislation in a phone call with her Irish counterpart, Simon Coveney, earlier on Monday. During the 12-minute call held at the U.K.’s request, Coveney warned the move would be “deeply damaging” to British relations with Ireland and the EU, according to an Irish Foreign Ministry statement.

Coveney also accused Truss of not engaging in meaningful negotiations with the EU since February. “Far from fixing problems, this legislation will create a whole new set of uncertainties and damage relationships,” he added.