Britain’s new Prime Minister Liz Truss on Wednesday appointed strongly pro-Brexit lawmaker Steve Baker to a junior ministerial role in the Northern Ireland Office, an appointment criticised as sending a “destructive message”.

Truss said earlier on Wednesday her preference was to find a negotiated settlement with the European Union to resolve the issues around the contentious rules that govern post-Brexit trade with Northern Ireland.

The stand-off over the Northern Ireland protocol is by far the biggest of several issues straining relations between the EU and Britain, and could lead to a trade war if London presses ahead with legislation effectively tearing up some of the rules.

The appointment of Baker, who headed a hardline Brexit faction in the Conservative Party during the Britain’s negotiations to leave the European Union, was criticised by some Northern Irish politicians.

Claire Hanna, a lawmaker for Northern Ireland’s nationalist SDLP, said Baker’s appointment was “an obnoxious decision that will send a destructive message to the European Commission and to parties in Northern Ireland”.

“Liz Truss has an opportunity to make the case for a negotiated resolution with the European Union in the interests of people across these islands. These appointments seem in stark contrast to that objective,” Hanna said in a statement, also highlighting the appointment of fellow hardline Brexiteer Chris Heaton-Harris as secretary of state for Northern Ireland.

Baker helped lead the rebellion which sunk then Prime Minister Theresa May’s Brexit deal, saying it kept Britain too closely shackled to the EU.