US Defense Secretary Robert Gates called for a comprehensive international dialogue on cyber attacks to prevent incidents from escalating dangerously out of control. \"We take the cyber threat very seriously and we see it from a variety of sources, not just one or another country,\" he told a security conference in Singapore on Saturday, also attended by his Chinese counterpart Liang Guanglie. Chinese hackers have been blamed for cyber attacks on US targets, a charge Beijing denies, but Gates stopped short of naming any country when asked about the issue at the annual Shangri-La Dialogue. Just days before, Internet giant Google said a cyber spying campaign originating in China had targeted Gmail accounts of senior US officials, military personnel, journalists and Chinese political activists. \"I think we could avoid some serious international tensions in the future if we could establish some rules of the road as early as possible that let people know what kinds of acts are acceptable, what kinds of acts are not, and what kinds of acts may in fact be an act of war,\" Gates said. Gates said the United States was under cyber attack \"all the time.\" \"There is no question that our defence systems are under attack all the time, fairly routinely in fact, and we\'ve taken a number of steps to try and protect ourselves,\" he added. On the sidelines of the conference, US aerospace giant Boeing said it was also under \"continuous\" cyber attack but there has been no breach of its databases. The admission by Dennis Muilenburg, chief executive of Boeing Defense, Space and Security, came as Japanese electronics giant Sony reeled from a series of online incursions. \"I think all countries should see the cyber threat as a potential problem for them,\" Gates said. \"One of the things that I have been trying to get going over the last four, four-and-a-half years, is to examine this world of cyber in the context of defense responsibilities, and what in fact does constitute an offensive act by a government.\" Gates said the process of understanding cyber attacks was still at an early stage. \"I think that one of the things that would be beneficial would be for there to be a more open dialogue among countries about cyber (threats) and establishing some rules of the road,\" he said. Gates said this would help achieve a \"clearer understanding of the left and right lanes, if you will, so that somebody doesn\'t inadvertently or intentionally begin something that escalates and gets out of control.\"