The problem lies in the complexity and vastness of China's supplier networks. "We're not talking about one nice, clean supply chain, where [Wal-Mart] can go to their tier 1 or tier 2 suppliers and be able to get this ability and eliminate some of the product quality, supplier and environmental risks," Tohamy says. "We're talking about a maze of supply chains." And as one moves downstream in each supplier's own supply chain, pushing far into operations of smaller manufacturers in Vietnam and Thailand, the visibility into supply chain information becomes narrower and narrower, she adds. (Wal-Mart media relations did not return repeated requests for comment.)

Michael Green, executive director of the Center for Environmental Health, a watchdog group in Oakland, Calif., told the that suppliers under pressure to offer Wal-Mart the lowest prices are likely to have an incentive to cheat, and outside auditors checking on suppliers' operations may not want to report violations for fear of losing big Wal-Mart contracts.

On the technology front, Tohamy points out that Wal-Mart is "dealing with very small suppliers that typically won't have the IT infrastructure that will allow them to give their customers--which are Wal-Mart's suppliers--visibility into what they're doing," Tohamy says. "The amount of data and criteria that we need to look at to make an educated decision on whether a supplier is abiding by whatever regulations and guidelines we need them to abide by, in terms of green and environment--this is not a manual exercise that anyone can go through." And if those small suppliers can't supply that data, how can Wal-Mart know if its suppliers are truly compliant?

Wal-Mart, of course, has a long history of pushing forward with IT-based supply chain initiatives--. The most recent example has been the various mandates that its U.S. suppliers affix radio-frequency identification (RFID) tags to goods moving throughout Wal-Mart's supply chain. (See CIO's articles in , , and for more on Wal-Mart's efforts.)

For all of the challenges Wal-Mart and its suppliers now face, however, Tohamy says the fact that Wal-Mart is embarking on the strategy is a big step in the right direction that will force other large companies to follow suit.