Britain will present legislation to parliament on Monday to unilaterally revise the post-Brexit trade arrangements for Northern Ireland, raising the risk of a trade war and a new clash with Brussels.

Foreign Secretary Liz Truss will present the bill to the House of Commons, according to a parliamentary order paper published on Friday.

Britain has been threatening for months to rip up the Northern Ireland Protocol, a trade deal for the British-run region that was struck by Prime Minister Boris Johnson’s government in order to secure a Brexit divorce and a wider trade agreement between Brussels and London.

London says the implementation of the protocol has damaged trade within the United Kingdom and threaten political stability in Northern Ireland.

The new legislation is designed to simplify the rules but has drawn sharp criticism in Brussels and Washington where it is seen by many as an inflammatory move that violates an international treaty.

European Commission vice-president Maros Sefcovic said in May that Brussels would respond with all measures at its disposal. U.S. House of Representatives Speaker Nancy Pelosi said there could be no U.S.-UK trade deal if London proceeds with the plan.

The protocol enabled Britain to leave the EU’s single market and customs union without controls being re-imposed on the border between the Irish Republic and Northern Ireland, vital to the 1998 Good Friday peace deal that ended three decades of violence.

By striking such a deal, it effectively agreed to a customs border between the British-run region of Northern Ireland and the rest of the United Kingdom.

The order paper said the bill will set out how the terms included in the protocol would now be defined in domestic law. There will not be a debate on the bill at this stage.

The Times newspaper reported this week that the legislation had undergone “substantial drafting and redrafting” after Johnson, badly weakened by a narrow victory in a confidence vote, came under pressure by his Brexit-backing lawmakers to toughen the terms.

However Johnson will need to secure support from all wings of the party to get the legislation through parliament. Four in 10 of his lawmakers voted to ditch Johnson in the confidence vote, and some have already expressed concern about the bill.