Both parties in Sudan's civil war are to blame for a looming mass famine, experts say, and the military's blocking of U.N. aid at a border crossing with Chad exacerbates the problem.

Sudan’s military is blocking United Nations aid trucks from entering at a key border crossing, causing severe disruptions in aid in a country that experts fear may be on the brink of one of the worst famines the world has seen in decades, The New York Times reported Friday.

The border city of Adré in eastern Chad is the main international crossing into the Darfur region of Sudan, but the Sudanese Armed Forces (SAF), the state’s official military, which is engaged in a civil war with a paramilitary group called the Rapid Support Forces (RSF), has refused to issue permits for U.N. trucks to enter there, as it’s an RSF-controlled area.