North Korea's lack of large airstrips and aircraft meant it conducted only minimal air resupply, mostly critical items being imported from China. Other than this, however, aircraft played almost no role in North Korean logistics. The North Koreans were also unable to effectively use sea transport. Ports in Wonsan and Hungnam could be used for the transport of some troops and supplies, but they remained far too underdeveloped to support any large-scale logistical movements, and the port of Inchon in the south was difficult to navigate with large numbers of ships.