STUTTGART, Germany — U.S. special operators on the ground in Bosnia coordinated with two U.S. Air Force F-16s flying overhead to rehearse a close air support mission with local forces, American officials said Monday.

The bilateral drill with Bosnia and Herzegovina amounted to a show of force at a time of tension in the country, where concerns are growing over a secessionist movement.

The military cooperation demonstrates the United States’ commitment to ensuring the territorial integrity of Bosnia and Herzegovina “in the face of anti-Dayton and secessionist activity,” the U.S. Embassy said in a statement Monday.

The embassy added that the U.S. “will act if anyone tries to change this basic element” of the 1995 Dayton Accords or the Bosnian constitution, which “provides no right of secession.”

In recent weeks, the leader of the Republic of Srpska territory, Milorad Dodik, has threatened to declare independence from Bosnia-Herzegovina. The territory is majority ethnically Serbian and comprises a little less than half of the nation’s land.

More than 100,000 people were killed in fighting in the Balkans prior to the accords, when Serbians in Bosnia tried to break away and join Serbia. The accords established Serb and Bosniak-Croat entities held together by joint institutions.

Dodik, who is backed by Russia, has defied U.S. and British sanctions over his policies, according to Associated Press reports.

On Tuesday, Dodik’s government plans to hold a celebration of a controversial national holiday that Bosnia’s top court has declared unlawful. On Jan. 9, 1992, Bosnian Serbs proclaimed the creation of an independent state in Bosnia, which led to the bloodshed.

Dodik has dismissed the U.S. jets’ flyover, saying it would contribute to Tuesday’s celebrations, which routinely include a parade of armed police and their equipment, the AP reported.

The drills in Bosnia involved air-to-ground training with Army Special Forces joint terminal attack controllers and local troops in the Tuzla and Brcko region.

“American support for Bosnia and Herzegovina’s Armed Forces is ironclad, forged over years of close cooperation,” U.S. European Command’s deputy commander, Lt. Gen. Steven L. Basham, said in a statement. 

JTAC teams provide close air support and are “used to direct the action of military aircraft from a forward position in support of ground forces,” the embassy statement said.

The mission was supported by a KC-135 Stratotanker that will provide aerial refueling for the F-16s over the Srpska territory, the embassy said.

The exercise was being led by U.S. Air Forces in Europe-Air Forces Africa with support from U.S. Special Operations Command Europe.

“U.S. aircraft will return to base immediately following mission completion,” the embassy statement said. “The ability to rapidly deploy, reach a target and return home demonstrates the United States’ ability to project power anywhere at a moment’s notice and operate alongside allies and partners.”