Mother Jones: The US Central Intelligence Agency is funding a project by the National Academy of Sciences to investigate human influence on weather patterns and the implications for national security. Some small geoengineering projects have been attempted in the past several decades. During the Vietnam War, for example, the US tried to gain a tactical advantage by seeding clouds to cause rain over the Ho Chi Minh Trail. China has also made forays into geoengineering, such as when it seeded clouds in advance of the 2008 Beijing Olympics to try to ensure good weather during the event. New, more ambitious projects include ways to reduce global warming; one example is solar radiation management, in which particles are pumped into the stratosphere to reflect sunlight away from Earth. However, the possibility that foreign countries or wealthy individuals might try to alter the climate to advance their own ends is raising concerns. The $630 000 NAS study will try to determine which techniques are feasible, and their impacts and risks.