Pak-China Border via Khunjerab top will re-open for trade and travel from Monday. According to protocol singed between both the friendly countries, the border remains closed from 1st of December to 1st of April every year due to heavy snowfall, Radio Pakistan reported. The Khunjerab Pass is the highest paved international border at an altitude of 15,500 feet; a daily bus service runs between the Sost valley of Gilgit-Baltistan and Xinjiang province of China.