One county in South Sudan is likely in famine and tens of thousands of people in five other counties are on the brink of starvation, according to a new report by international food security experts.

Nowhere in the world has been in famine since one was declared nearly four years ago in South Sudan's Unity state as civil war raged. Now western Pibor county is feared to have reached that crisis level, the result of massive flooding and deadly violence that has prevented access to aid.