UNITED NATIONS (AP) — The United Nations is welcoming the arrival of the first food convoy from Sudan to northern South Sudan as a step forward in relations between the feuding neighbors.

U.N. deputy spokesman Farhan Haq said Monday that the World Food Program's ability to deliver food by road will expedite the delivery of aid.

WFP said using trucks and river barges will reduce costly air transport to conflict-affected areas in South Sudan.

It said 18 trucks transporting 700 metric tons of food for about 45,000 people for one month arrived in Upper Nile State from the port of Kosti. WFP aims to deliver 4,650 metric tons to northern South Sudan for about 275,000 people for a month.

South Sudan broke away from Sudan in 2011 after decades of war but relations remain tense.