Operation Ranch Hand, a U.S. Air Force program to use C-123K aircraft to spray herbicides over large areas was one of many programs under Operation Trail Dust. The aircrews charged with spraying the defoliant used a sardonic motto-"Only you can prevent forests"-a shortening of the U.S. Forest Services famous warning to the general public "Only you can prevent forest fires". The United States and its allies officially claims that herbicidal and incendiary agents like napalm fall outside the definition of "chemical weapons" and that Britain set the precedent by using them during the Malayan Emergency.