1. A method of allocating inventory across a plurality of locations in a supply chain, the method comprising: determining a baseline inventory for one or more items at each location in the supply chain based on expected values for demand for each of the one or more items and lead time for each location in the supply chain; determining a total time-phased inventory and target safety stock level for each of the one or more items at each location in the supply chain based on the baseline inventory, a target service level, a demand uncertainty level for each of the one or more items, a lead time uncertainty level for each location in the supply chain and carrying costs in the supply chain; determining a constrained safety stock level for each of the one or more items at each location in the supply chain; and determining production, procurement and transfer supplies to achieve the constrained safety stocks.