Recent years have witnessed the pervasive supply disruptions and their impacts on supply chain performance. In this study, we investigate the optimal procurement design with supply disruptions and heterogeneous beliefs between the buyer and the supplier. We examine the impact of information asymmetry on the supplier's belief, the control right of the backup production, and the verifiability of supply disruption. The belief heterogeneity creates speculative gains and losses because the buyer and the supplier hold different estimates of the disruption probability. We demonstrate that the buyer's incentive to exploit this belief heterogeneity leads to real production inefficiencies in different scenarios. The production efficiency is not necessarily improved with more transparent information. Moreover, a very pessimistic supplier may have no incentive to invest in improving the reliability even if this is costless, and the supplier may produce more when the expected production cost becomes higher. When the buyer sees some value in using the supplier's estimate to update his own belief, we find that the main results hold unless the buyer completely abandons his belief.