As an estimated 6,000,000 Chinese head home by rail for Chinese New Year, security has been tightened at railway stations and transport hubs in Beijing, Guangzhou, Shanghai,Hangzhou and other cities across China. Guo Shengkun, China's Minister for Public Security and Head of the National Anti-terrorism Leadership Group, told members of the Group at a meeting in January 2016, that “The relevant departments … must put all their efforts into their anti-terrorism and security duties, and ensure social stability and public safety.” Li Wei, an anti-terrorism researcher at Tsinghua University’s Institute of Modern International Relations in Beijing, said “Intensifying security checks might be the major way of preventing terrorist attacks.” Describing the East Turkistan Islamic Movement (ETIM), which had conducted most of the past attacks, as the biggest threat to China, he added “The Islamic State is also strengthening its propaganda through the internet in China and has radicalised many people.” Security forces have also recruited volunteers and Beijing's Xicheng District, for example, has up to 70,000 grassroots public security volunteers, nicknamed “Xicheng Grannies”, who are credited with reporting 72 terrorist-related incidents while monitoring their local communities in 2015.