I think the Tamil Tigers were Hindu, you might check on that. Regardless, Buddhism is not a pacifist religion, although pacifism is often encouraged and ignored -- like vegetarianism.
During the American war there were several monks who immolated themselves to protest the Roman Catholic government's efforts to suppress Buddhism. They are now celebrated with squares and roundabouts named after them, in spite of the government's ambivalence toward religions. There have also been a few cases of this in Tibet recently.
Japanese Buddhist behavior during the second world war is a matter of much discussion in SE Asia, and much hand wringing. Buddhists almost never will reject another flavor of Buddhism (they are called "sects," but that is misleading since none of them deny the validity or value of the others), so the validity of Japanese Buddhist un-Buddhist like behavior is not brought up, leading to a true internal contradiction.