JUBA, South Sudan — The World Food Program says South Sudan’s government has suspended “lifesaving airdrops of food assistance,” the latest obstacle humanitarian officials have faced in this troubled country.

The halt of airdrops is due to a “misunderstanding regarding flight clearances,” and the issue is likely temporary, WFP spokesman Challiss McDonough told The Associated Press. The U.N. agency has seen its airdrops briefly suspended in South Sudan before.

This East African country, the world’s youngest nation, faces one of the world’s worst humanitarian crises. Civil war that began in late 2013 made widespread hunger problems worse. The government says food prices in some areas are 10 times higher than a year ago.

WFP says more than four million people face food insecurity. The country’s population has been estimated at more than 12 million, though thousands of people continue to flee to neighboring states.

South Sudan has been criticized for blocking aid delivery amid some officials’ hostility at the international community. Additional restrictions on U.N. and other aid convoys are necessary to ensure security, Minister of Cabinet Affairs Martin Elia Lomoro told the AP in an interview last week.

“We are in a war situation, and we don’t know who among you may be doing something with the rebels,” Lomoro said.

Since fighting in the capital, Juba, killed hundreds of people in July, South Sudan has seen clashes across the country, and restrictions on humanitarian access have sharply increased.

When the U.N. Security Council visited the country in September, the government pledged to “immediately improve humanitarian access.”