The US defence agency that invented the forerunner to the internet is working on a virtual firing range" intended as a replica of the real internet so scientists can mimic international cyberwars to test their defences. Called the National Cyber Range, the system will be ready by next year and will also help the Pentagon to train its own hackers. The move marks another rise in the temperature of the online battlefield. The US and Israel are believed to have collaborated on a sophisticated piece of malware called Stuxnet that targeted computers controlling Iran's nuclear centrifuge scheme. The Defense Advanced Research Projects Agency (Darpa), which developed Arpanet, the forerunner of the internet, in the 1960s, is working on a number of fronts. Barack Obama has asked Congress for more than $250m (154m) to fund Darpa's cyber initiatives in the coming year, double his fiscal 2011 request. The National Cyber Range is expected to be working by mid 2012, four years after the Pentagon approached contractors to build it at an estimated $130m. Darpa will this summer select one of them to operate a prototype test range during a year-long test. It will also help train cyberwarriors such as those in the American military's Cyber Command, ordered up by the secretary of defence, Robert Gates, in June 2009.