Transport in Bhutan uses about 8,000 kilometres (5,000 mi) of roads and four airports, three of which are operational and interconnected. Paro Airport is the only airport which accommodates international flights. As part of Bhutan's infrastructure modernization programs, its road system has been under development since the 1960s. There are no railways (although one is planned), and as Bhutan is a landlocked country with no major waterways, there are no ports.