BELGRADE, Serbia — A Serbian train bearing signs reading “Kosovo is Serbian” has been halted at the border with Kosovo, fueling a crisis in the Balkans and escalating a potential contest between Russia and the West over dominance in the region.

Serbia accused Kosovo’s leaders on Sunday of “wanting war” and warned that it would defend “every inch” of its territory, a day after the train, decorated in Serbian Christian Orthodox symbols and flags, was prevented from entering the neighboring nation.

Kosovo, supported by much of the West, declared independence from Serbia in 2008. But Serbia and its Slavic Orthodox ally, Russia, do not recognize the split.

Serbia has sought to maintain influence in Kosovo’s north, where most of the country’s Serbian minority lives. Troops led by NATO have controlled Kosovo’s borders since a three-month air war in 1999 to stop a bloody Serbian crackdown against ethnic Albanian separatists.