True, . engagement and greater international involvement requires effort. But the wait-and-see approach will prove far more costly. The Bosniaks and Croats went to war in 1992 to keep Bosnia together, and there is no indication that today they’d be willing to let Republika Srpska go without a fight. Should violence erupt, it will be felt across the Balkans. It could spill over to Kosovo, south Serbia, Macedonia, and the Muslim-majority Serbian region of Sandzak. And spillover from Bosnia could disrupt ongoing talks between Belgrade and Pristina over the normalization of relations. It could bring a return of the ethnic cleansing of the 1990s and renewed refugee flows. It could also radicalize Bosnia’s moderate Muslims, who are under growing pressure from extremist Gulf elements, risking the creation of an angry, Muslim-majority ministate directly on the EU’s border.