Pro-unification demonstrators crowded the centre of Moldova’s capital Chisinau on March 25, demanding that the government support a bill that would call for the unification of the small, land-locked former Soviet republic with its far larger western neighbour.

Romania’s lawmakers responded to the demonstrations across the border by holding a symbolic vote in the parliament saying they expressed support for unification with Moldova, a move that was not endorsed by Bucharest’s counterparts in C...