The Air Force F-35 is using “open air” ranges and computer simulation to practice combat missions against the best Chinese and Russian-made air-defense technologies – as a way to prepare to enemy threats anticipated in the mid-2020's and beyond. The testing is aimed at addressing the most current air defense system threats such as Russian-made systems and also focused on potential next-generation or yet-to-exist threats, Air Force officials said. Air Force officials have explained that, looking back to 2001 when the JSF threat started, the threats were mostly European centric – Russian made SA-10s or SA-20s. Now the future threats are looking at both Russian and Chinese-made and Asian made threats.