Citizens and students pose for a photo during an activity themed on National Security Education Day at the Hong Kong Police College in south China's Hong Kong, on April 15, 2021. Hong Kong on Thursday embraced its first National Security Education Day after the law on safeguarding national security in the Hong Kong Special Administrative Region (HKSAR) came into force in mid-2020. Various activities, including lectures, exhibitions, mosaic walls and doors open days of disciplined services, were held to boost the public awareness of safeguarding national security in the global financial hub. (Xinhua/Li Gang)