Savannakhet, officially named Kaysone Phomvihane ; since 2005 and previously known as Khanthaboury, is a city in western Laos. It is th…Savannakhet, officially named Kaysone Phomvihane ; since 2005 and previously known as Khanthaboury, is a city in western Laos. It is the capital of Savannakhet Province. With a population of 125,760, it is the second-largest city in Laos, after Vientiane. The annual per capita income of Kaysone Phomvihane City is US$2,041.