Britain imposed sanctions on two leading Bosnian-Serb politicians on Monday, accusing them of encouraging ethnic hatred and jeopardising the peace accord that ended the civil war in Bosnia-Herzegovina more than 25 years ago.
“These two politicians are deliberately undermining the hard-won peace in Bosnia and Herzegovina,” Ms Truss said.
“Encouraged by Putin, their reckless behaviour threatens stability and security across the Western Balkans.”
UK authorities say the two have have used their positions to push for the de facto secession of Republika Srpska — one of two semi-autonomous regions that comprise the federation of Bosnia and Herzegovina — in direct contravention of the country’s constitution.
The US Treasury Department on Monday imposed its own sanctions on seven more people from the Western Balkans.
Mr Dodik has for years advocated separating the Bosnian Serb mini-state from the federation and uniting it with neighbouring Serbia.
He is the Bosnian-Serb member of Bosnia’s tripartite presidency, which also includes representatives of the Bosnian Muslim and Croat communities.
Secession would violate the Dayton Accords, the 1995 US-sponsored agreement that ended Bosnia’s civil war, which killed more than 100,000 people and left millions homeless.
The agreement established two separate governing entities in Bosnia — one run by Bosnia’s Serbs and the other controlled by the country’s Bosniaks and Croats.
The two entities are linked by joint institutions, and all actions taken at a national level have to be reached by consensus among the three ethnic groups.
US authorities had earlier placed sanctions on Mr Dodik, accusing him of “corrupt activities” that threaten to destabilise the region.
They allege that he used his leadership position to accumulate wealth through graft and bribery.
Ms Cvijanovic, the President of Republika Srpska, the Serb entity, proposed legislation to transfer power from the national government to her mini-state, British authorities said.
She has also glorified war criminals and denied acts of genocide during the civil war, US fficialsthey said.
The top UN official in Bosnia, Christian Schmidt, described the decision to impose sanctions on Mr Dodik and Ms Cvijanovic as “reasonable” and thanked the British government for its commitment to Bosnia’s stability and security.
“Dodik and Cvijanovic missed every opportunity to get back into constructive dialogue for the benefit of the people in this country,” said Mr Schmidt, the UN’s high representative for Bosnia-Herzegovina.
“They will have to bear the consequences of their words and deeds, and the UK sanctions are the continuation of the consequences that started in January with the US sanctions.”
The practical impact of Monday’s actions is unclear. Mr Dodik and Ms Cvijanovic have said they do not have assets in the UK.
“All they (British) say are lies," Mr Dodik said. "They are old manipulators and enemies of the Serb people. I told them so many times before.
“They are helpless in their feud with Putin and they accuse the two of us now of acting on orders from Putin."
Andi Hoxhaj, an expert in corruption in the Western Balkans at Warwick Law School, said the new sanctions were “appropriate.”
The lack of a clear European Union strategy to integrate the Western Balkans has created a vacuum that has allowed Russia and China to undermine democracy and pursue their own goals in the region, Mr Hoxhaj said.
“However, with the ongoing war in Ukraine, there is a policy shift to sanction individuals that undermine peace and democracy in fragile states, and this attempt is to address that."
The US on Monday also added seven more people and a company in Hungary to the list of people and businesses from across the Western Balkans that have been sanctioned for corrupt and destabilising activity.
“The people designated today constitute a serious threat to regional stability, institutional trust, and the aspirations of those seeking democratic and judicious governance in the Western Balkans,” said US Treasury undersecretary for terrorism and financial intelligence, Brian Nelson.
The list includes people from Albania, North Macedonia, Bosnia-Herzegovina and Montenegro.
The most prominent are a former president of the former joint state of Serbia and Montenegro, Svetozar Marovic, former North Macedonian prime minister Nikola Gruevski and Gordana Tadic, a one-time chief prosecutor in Bosnia-Herzegovina.
The sanctions mean that any property they own in the US will be frozen and business transactions with American companies are banned.
Those from Bosnia-Herzegovina and North Macedonia, along with their immediate family members, are also barred from travelling to the US.
“The ultimate goal of sanctions is not to punish but to bring about a positive change in behaviour,” the Department of Treasury said.