People watch acrobatic performance during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo: Ammar Safarjalani/Xinhua)

Syrians set free balloons during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo: Ammar Safarjalani/Xinhua)

A dancer performs traditional whirling dance during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo: Ammar Safarjalani/Xinhua)

Syrians set free balloons during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo: Ammar Safarjalani/Xinhua)

Syrians set free balloons during a celebration marking the International Day of Peace at the Umayyad Square in Damascus, Syria, on Sept. 21, 2019. Various activities were held in Damascus on Saturday to mark the International Day of Peace, which falls on Sept. 21 each year. (Photo: Ammar Safarjalani/Xinhua)