From a "jihadi university" in the Syrian city of Raqqa, the scientists have stunned western weapons experts by producing a homemade thermal battery for surface-to-air missiles. It had been regarded as a virtually impossible feat for terror groups working without a military infrastructure. But footage exclusively obtained by Sky News shows that IS can now recommission thousands of missiles assumed by western governments to have been redundant through old age. SUBSCRIBE to our YouTube channel for more videos: http://www.youtube.com/skynews Follow us on Twitter: https://twitter.com/skynews and https://twitter.com/skynewsbreak Like us on Facebook: https://www.facebook.com/skynews Follow us on Instagram: https://www.instagram.com/skynews For more content go to http://news.sky.com and download our apps: Apple https://itunes.apple.com/gb/app/sky-news/id316391924?mt=8 Android https://play.google.com/store/apps/details?id=com.bskyb.skynews.android&hl=en_GB