 One study questions these findings, showing that alliance commitments deterred conflict in the prenuclear era but has no statistically meaningful impact on war in the postnuclear era.Another study finds that while alliance commitments deter conflict between sides with a recent history of conflict, alliances tend to provoke conflicts between states without such a history.A 2000 study in the "Journal of Conflict Resolution" found that allies fulfill their alliance commitments approximately 75% of the time.