By Emma Farge PAYERNE, Switzerland (Reuters) – The heads of the U.S. and Swiss air forces stressed the need for Western countries to strengthen security cooperation at an event on Tuesday that highlighted neutral Switzerland’s increasingly assertive role in world affairs. The generals watched a Swiss pilot fly a Hornet fighter in a simulation flight that was part of an official visit aimed at boosting cooperation as Bern prepares to receive more U.S. fighter jets by 2025. “Recent events underscore the importance of working together to strengthen our strategic partnerships in order to meet our …