A poster of the Day of Remembrance for the Victims of the NATO Aggression is seen in Nis, Sebia, on March 24, 2019. Serbia cannot forgive NATO for the thousands of civilians killed in 1999, Serbian President Aleksandar Vucic said here on Sunday, two decades after the beginning of the NATO bombings. Under the slogan "We will forgive if we can, but we will forget only if we perish", leaders of the country, church and military, ambassadors and citizens gathered in downtown Nis with lit candles to mark the Day of Remembrance for the Victims of the NATO Aggression. (Xinhua/Shi Zhongyu)