"We're hoping we can do anything we can to avoid another conflict in Europe from emerging," Rubio told reporters as he flew to Jeddah for talks on Ukraine.

"We're certainly reviewing all of our options," he said when asked about potential US action against Bosnian Serb leaders.

"We don't want to see partition there," he said. "Whatever differences may exist internally there, this cannot lead to the country breaking apart."

Bosnian Serb leader Milorad Dodik has defied the high representative charged with overseeing the peace accords that ended Bosnia's 1990s war and escalated further, forbidding access by the country's federal police and judiciary to the Republika Srpska statelet he leads.

Rubio, who had earlier accused Dodik of jeopardising Bosnia's stability, has stood with NATO and European allies on the political crisis despite headwinds in the transatlantic relationship.

US President Donald Trump has broken with European allies by demanding that Ukraine make concessions to Russia, which launched a full-scale invasion of Ukraine in 2022 and is a historical ally of Serbia.