One of my favorite lines (or translations, to be specific) in the Art of War (Sun Tzu) is the following: "In hemmed-in situations, you must resort to stratagem. In desperate position, you must fight." I would think that when dealing with suppliers in markets such as China where raw material and commodity price fluctuations can disproportionately affect pricing and even the basis of buyer/supplier relationships, we often resort to fighting when in fact we should first rely on "stratagem." In other words, as the quote suggests, we're "hemmed-in" rather than desperate. What are the implications (and strategies) given this slightly different approach in working with suppliers -- rather than truly going to war and fighting -- that won't hold contracted prices or will not offer to lock-in pricing beyond the next containers? Here are a few thoughts.
First, consider the bigger picture of the relationships with a particular supplier. If the behavior is representative of a broader trend of behavior inconsistent with what we expect in the West from a buyer/supplier relationship, consider a signal of the need to find a better longer-term partner. If the type of behavior has not occurred before, consider it an entrée to probe on the real issues surrounding the rationale behind the sudden change in relationship.
Second, in any such situation, it is important to understand the motivations behind the supplier's move (unless we should really be thanking the supplier for making the decision for us to exit the broader relationship, as discussed above). Indeed, such a demand of contract term changes can invite questioning we might not find easy to ask of Chinese suppliers under other circumstances such as their banking relationship, credit terms suppliers are extending to them, general ability to buy forward, etc. Such a discovery process can be enlightening, and in fact ultimately lead to a better outcome for both parties (e.g., the decision to help a supplier buy forward by providing either financing, early payment for existing invoices, aggregating the buy across multiple tiers and suppliers, or through other means).
Most importantly, show true force only when necessary. And in those cases, make it decisive and overwhelming. After all, many Chinese follow the school of Sun Tzu in business relationships. Shouldn't we?