A pair of U.S. Air Force B-1B Lancer bombers flew low over Sarajevo and several other Bosnian cities on Tuesday as a sign of support amid continued secessionist threats by the staunchly pro-Russia Bosnian Serb leader Milorad Dodik.

In addition, the aircraft also participated in a joint military event in the north-eastern town of Tuzla with Bosnia’s multi-ethnic army and U.S. Army Special Forces.

The flights were a demonstration of “a rock-solid commitment to the sovereignty and territorial integrity” of Bosnia, said the U.S. ambassador to the Balkan country, Michael Murphy.

Murphy added that United States “remain steadfast and committed” to the relationship with the Bosnian armed forces “in the face of political stability within (Bosnia) and acute threat from malign actors outside” the country.

Dodik, who is the president of Bosnia’s Serb-run part, Republika Srpska, has repeatedly advocated for the breakup of the country and voiced his admiration for Russian President Vladimir Putin. Earlier this month, he travelled to Moscow to meet with Putin and reiterate his support for Moscow’s invasion of Ukraine.

He reacted angrily to the flight over Bosnia by U.S. bombers, accusing Washington of “disrespecting” the country’s territorial integrity and treating it “as a guinea pig that they can suffocate and cut off its air supply for as long as they want.”

A U.S.-brokered peace deal in 1995 ended a nearly 4-year-long internecine war in Bosnia that left at least 100,000 people dead and millions homeless. It left the country deeply divided between its three main ethnic groups - Muslim Bosniaks, Orthodox Serbs and Catholic Croats. The Dayton Peace Accords split Bosnia into two highly autonomous entities - Republika Srpska and one dominated by mostly Bosniaks and Croats - linked by shared, state-wide institutions.

Russia has been exploiting the divisions by supporting Dodik’s separatist policies, raising fears in the West that the Kremlin might use him to create further instability in the volatile Balkan country to divert some attention from its war in Ukraine.