China is building a nuclear missile silo field in the west of the country, US scientists say. Satellite images from Xinjiang province suggest the site could house about 110 silos when it is finished, says the report from the Federation of American Scientists (FAS). US defence officials have expressed concern about China’s nuclear build-up. It is the second new silo field reported to be under construction in western China in the last two months. Last month, the Washington Post newspaper reported 120 silos spotted at a site in a desert area in Yumen, in Gansu province. The FAS said in its report on Monday that the new site at Hami, about 380 km (240 miles) north-west of Yumen, was at a much earlier stage of development.