The UN World Food Programme or WFP said it resumed food deliveries to South Sudan from its main air base at Lokichokkio in northwestern Kenya.
WFP eight weeks ago was disrupted by heavy floods.
In a statement, the agency said it was forced to relocate its South Sudan food operations to Eldoret, western Kenya in May when the floods swept away a key supply bridge.
WFP said it was able to construct a diversion through which food and fuel trucks were now being pulled over the steep riverbanks by a bulldozer.
The agency did everything possible to resume air operations in Lokichokkio as soon as possible and to ensure the most vulnerable people in South Sudan continue to be fed, said the statement.