The mainland's reaction to the submarine accident that cost 70 lives marks a significant departure from the traditional secretive approach taken to the nation's military disasters. But the extent to which it can be seen as evidence of a new era of openness remains unclear. News of the tragedy was revealed by Xinhua, the official news agency, on May 2. This was, in itself, an unprecedented step. Never before had the mainland authorities reported a military disaster. The announcement was swiftly followed, at the end of last week, by the revelation that many senior officers had been sacked or demoted as a result. Again, this decisive move broke new ground, amounting to the biggest single disciplinary action ever taken against senior PLA commanders. The decision to publicise the tragedy was a welcome sign of greater transparency. Removing the top officials responsible could be similarly interpreted as a determination by the leadership to make the military more accountable. Yet, more than six weeks after the accident was disclosed, hardly any information has been revealed about the circumstances in which those on board met their deaths. And while we now know who has been blamed, we have little understanding of why the officers concerned were punished. The Ming Class submarine No 361, a conventional diesel-powered vessel, was apparently found by fishermen off the coast of Shandong province, who saw its periscope sticking out of the water. It was a gruesome discovery. All 70 members of the crew had perished. So far, the official explanations have raised more questions than they have answered. Xinhua has attributed the disaster both to 'mechanical malfunction' and, more recently, to 'improper direction of the vessel's operations'. The lack of more detailed information has prompted a wide range of theories from analysts around the world, including a torpedo explosion, an electrical fault or the emission of toxic gas. One suggestion which gained currency was that a crewman had mistakenly opened the air release - rather than the air intake - valve. But this does not explain why all the crew members in different compartments died, or why no distress signal was sent. Amid all the speculation, the mainland authorities have remained virtually silent. Announcing disciplinary action against officers on Friday, Xinhua said the move followed 'the release' of the results of an investigation into the accident. But the details of the inquiry or its findings have not been made public. Little is known about the reasons for the disciplinary action, although heads have rolled at the top. Among those removed were the navy's commander and political commissar. In total, 12 officers have been dismissed or demoted. But the basis upon which they were held responsible has not been revealed. Until this happens, it is not possible to judge whether the right people have been punished, or if they have simply been made scapegoats for the disaster. The tough action taken by the mainland's leaders over Sars - sacking officials responsible for misconduct and allowing wide coverage in the media - helped establish an image of a more open and transparent government. If that perception is to be enhanced, the truth about this tragedy must be told. Only a full explanation of how those sailors met their death will suffice. This would not only boost China's credibility. It would do much to ease the pain of the victims' loved ones. They have already received the condolences of the leadership. But revealing the truth would help make good President Hu Jintao's soothing statement that those who died were 'not only your family, but ours'.