The United States became the first country in the world to develop a fifth-generation fighter jet when the F-22 Raptor came into service in 2005 (discounting the F-117 Nighthawk). Today, a number of countries are developing fifth-generation or what are claimed to be fifth-generation fighter jets. While there is no set definition of what qualifies as a fifth-generation fighter jet, plenty of countries are building jets with fifth-gen characteristics (such as being low-observable). Here are five jets in development with enhanced stealth features.