The United States has warned South Sudan government against preventing humanitarian assistance from reaching areas affected by famine.

The United Nations has declared a famine in some parts of South Sudan, where 5.5 million people face food shortages.

Deputy U.S. Ambassador Michele Sison warned Kiir’s government on Thursday that preventing aid workers from reaching parts of the country that are suffering famine could “amount to deliberate starvation tactics.”

“The famine is not a result of drought. It is the result of leaders more interested in political power and personal gain than in stopping violence and allowing humanitarian access,” Sison told the UN Security Council.

Photo: A young South Sudanese refugee cooks food at a camp in northern Uganda (UNHCR/Will Swanson)