Indian warships are at risk due to lack of Advanced Towed Array Sonar (ATAS), which are crucial for detecting submarines in warm, shallow waters and detecting threat. Earlier in mid 1990's, the Defence Ministry has blocked the purchase of ATAS, as the Defence Research and Development Organisation (DRDO) started with the development of an indigenous ATAS called Nagan. However, in 2012, the Nagan project was officially shut down and the DRDO began work on another system called ALTAS, that too has not been operationalised either. Also in 2009 a German company, Atlas Elektronik GmbH won the contract to supply six ATAS for some Rs 300 crore, but the deal was also deferred. As of now, DPSU Bharat Electronics Ltd is building 10 ATAS in partnership with a foreign vendor and most likely eighty advanced sonars are to be tendered over the next three years.