States also have great difficulty resolving competing claims over water rights. Uncertainty about water resources can introduce a strong status quo bias. States are typically extremely defensive about trading claims to water or relinquishing claims to water in exchange for something else when the implications of such trades are not well understood. It takes considerable time and effort for States to understand what they are trading and what deals are possible on Transboundary Rivers. Uncertainty over the terms of trade can create openings for offensive, unilateral actions, especially when neighboring States are unsure of the basic hydrological realities.