The United States on Monday imposed sanctions against four top Bosnian Serb officials, including the Serb member of the country’s presidency, for undermining a U.S.-sponsored peace deal that ended the Balkan country’s war in the 1990s.

Bosnia’s presidency member Zeljka Cvijanovic, along with the prime minister, justice minister and parliament speaker of the Serb Republic, facilitated the passage of a law that undermines the Bosnian constitution, U.S. State Department spokesman Matthew Miller said in a statement.

The constitution is part of the Dayton peace accords that ended the 1992-1995 Bosnian war in which 100,000 were killed, dividing the country into two autonomous regions, the Serb Republic and the Bosniak-Croat Federation, linked via a weak central government.

Late in June, lawmakers in the Serb Republic voted to suspend rulings by Bosnia’s constitutional court, a vote initiated by the region’s separatist pro-Russian President Milorad Dodik, who is already under U.S. and U.K. sanctions.

The U.S. Department of the Treasury designated Cvijanovic, Prime Minister Radovan Viskovic, Justice Minister Milos Bukejlovic and parliament speaker Nenad Stevandic for obstructing and threatening the implementation of the Dayton accords by providing the passage of the law.

“This action threatens the stability, sovereignty, and territorial integrity of Bosnia and Herzegovina and the hard-won peace underpinned by the Dayton Peace Agreement,” said Under Secretary of the Treasury for Terrorism and Financial Intelligence Brian E. Nelson.

“This behavior further threatens the country’s future trajectory and successful integration into Euro-Atlantic institutions,” Nelson added.

Cvijanovic was put under U.K. sanctions last year along with Dodik for what were described as attempts to undermine the legitimacy and functionality of the Bosnian state.

In reaction to the sanctions, Stevandic said that he saw them as a “decoration for consistency, steadfastness and non-indulgence in the face of blackmail and threats from those considered powerful.”

A spokesman for Dodik’s ruling SNSD party said the U.S. decision was “shameless and hypocritical.” “No sanctions will prevent us from doing our job,” Radovan Kovacevic said.

The designations build on prior U.S. sanctions and visa restrictions designed to promote accountability of persons who undermine democratic processes or institutions, the U.S. Department of the Treasury said.

Dodik and his allies have long promoted the secession of the region from Bosnia and its unification with neighboring Serbia. They stepped up activities undermining state institutions in recent months, including suspension of decisions by an international peace envoy.