Watch: Zhang's interview on laser weapons China's thick smog is the best defence against US laser weaponry, a PLA researcher said in a state television interview, after the American navy recently announced it was preparing to deploy its first laser weapon aboard a transport ship. Navy Rear Admiral Zhang Zhaozhong, a military expert at the National Defence University, said on CCTV's Haixia Liangan (Cross-Straits) current affairs programme last week that the lasers were "most afraid of smog". "Under conditions where there is no smog, a laser weapon can fire [at a range of] 10 kilometres. When there's smog, it's only one kilometre. What's the point of making this kind of weapon?" he asked. Echoing previous claims by state media that air pollution had an upside when it came to defence, Zhang explained that smog was made up of tiny metallic particulates - and the higher their PM number (the particles' diameter in micrometres), the harder it would be for lasers to penetrate. The Associated Press reported last week that the US Navy planned to deploy its first laser weapon aboard the USS Ponce, a nearly 17,000-tonne transport dock that will be stationed in the Middle East. The laser weapon is designed to fire beams that can burn through drones and smaller boats, the report said. Zhang's assessment immediately drew criticism on the popular Sina Weibo social media site, where the news was reposted and commented on more than 10,000 times. In response, the rear admiral told the Beijing Youth Daily that his statements were taken out of context, and urged his detractors to watch the entire interview before passing judgment. Zhang noted that he talked about laser weapons on the show for 12 minutes, but the interview was edited into a two-minute clip, featuring soundbites that led to some "misunderstanding". "I just stated a laser weapon's weakness," Zhang said. "I don't support smog." The version that aired on CCTV also featured Zhang saying that the laser weapon's enemy at sea was saltwater spray, which could rust or damage it. "What I said was totally accurate, 100 per cent without error. What other people said is second or third-hand interpretation." Zhang declined to comment on Beijing's smog, which he said was not his area of expertise. China's northern regions were blanketed in smog yesterday, and Beijing has issued an "orange" pollution alert - the second-highest on the scale. Under the orange alert, construction sites are requested to stop building activities, and major industrial plants need to either suspend operations or reduce production by 30 per cent. All outdoor barbecues are also banned. Schools and kindergartens are advised to cancel outdoor activities. The environmental authorities have encouraged residents to stay indoors as much as possible and to put on masks when they have to go out. The US embassy air-quality monitor in the capital reported "hazardous" levels of the most dangerous PM2.5 particles yesterday - 405 micrograms per cubic metre at 1pm, significantly higher than the Ministry of Environmental Protection's reading of 270. According to the ministry, Tianjin was "lightly polluted", with a PM2.5 count of 125, five times the World Health Organisation's guideline, while the cities of Shijiazhuang, Baoding and Cangzhou in Hebei province had 292, 267 and 153 respectively. Note: An earlier version of this article misstated Zhang Zhaozhong's rank. He is a rear admiral, not a major general.