Governance in South Sudan has been undermined by corruption and ethnic fighting since a 2018 peace agreement ended five years of bloody civil war in the young nation, which gained independence from Sudan in 2011.

The US State Department did not name the individuals it was sanctioning, only saying they "participated in obstructing life-saving humanitarian aid through the taxation of aid shipments."

"These persons may be found ineligible for entry into the United States," it said in a statement.

It added that the United States was "deeply concerned" about the failure of South Sudan's transitional government -- established in the 2018 deal -- to establish a system to fully implement its obligations under the peace agreement.

In particular, it noted that the government was obliged to create an "enabling" environment to allow for the delivery of humanitarian assistance.

The 2018 deal paved the way for a power-sharing government and laid out a roadmap for political transition and elections.

But in August 2022, South Sudan's leaders agreed to extend the transitional period for another 24 months, to February 2025, and elections have been tentatively set for December 22 this year.

However, key tenets of the agreement are still incomplete, including the creation of a national constitution.