More than 200 Chinese and Pakistani troops held joint anti-terrorism exercises in China's mainly Muslim northwestern region of Xinjiang on Friday, the Xinhua news agency said. The anti-terror drills were the first between the neighbouring countries that have been allies for decades and boast an "all-weather" friendship, although they held naval exercises last October off Shanghai. "The joint command headquarters drill included information exchange and situation assessment, and the troops drill practiced encirclement, assault and mop-up," Xinhua said quoting People's Liberation Army sources. China has backed the U.S.-led war on terror, calling for international support in its campaign against ethnic Uighur separatists in Xinjiang, a mostly Muslim region that has borders with Afghanistan and Pakistan. The military officers took part in the first such land drills with Pakistan, codenamed "Friendship 2004", in an area of Xinjiang bordering Kashmir, a volatile territory claimed by India and Pakistan and parts of which are also disputed by China. The goal of the exercises, in 4,000 metre (13,120 ft) high mountains, was to "improve the capacity of jointly combating terrorism, and contain and crack down on the forces of separatism, extremism and terrorism", Xinhua quoted unidentified Chinese military sources as saying. China usually shrouds such military drills in extreme secrecy. Last week, Pakistan formally approved proposals to build a new nuclear power plant with help from China.