James Nando and Alfred Futuyo were found to have abused their positions to carry out acts of sexual violence against citizens.
The United States on Tuesday sanctioned two South Sudanese officials in relation to "conflict-related sexual violence", alongside two leaders of the Islamic State (IS) group.
The Treasury Department said that the moves were the first results of a dedicated US government focus on conflict-related sexual violence, following a memorandum on the issue signed by President Joe Biden last November.
"In the case of South Sudan, the two individuals designated were found to have abused their positions of political and military authority to carry out acts of sexual violence against citizens," the Treasury Department said.
These included cases of abduction and rape that happened under the individuals' watch, or in which they participated.
The two South Sudanese officials were named as James Nando, a major general in the South Sudan People's Defence Forces, and Alfred Futuyo, governor of Western Equatoria.
"Futuyo is also affiliated with the Sudan People's Liberation Movement/Army," the department added.
Biden, in a separate statement, said that "the United States is committed to doing all we can to end this blatant abuse of human rights", while noting that sexual violence in conflict continues to be widespread.
The Treasury's designations were accompanied by similar State Department actions targeting two IS leaders for allegedly committing sexual violence against Yezidis, and their responsibility over the abduction and enslavement of women and girls.
"Today's designations, along with sanctions on ISIS leaders by the US Department of State, represent the first time that a dedicated focus on conflict-related sexual violence... has led to the imposition of US sanctions," the Treasury Department said.
The IS leaders are senior field military commander Arkan Ahmad 'Abbas al-Matuti, and Nawaf Ahmad Alwan al-Rashidi -- who manages IS financial payments to members and widows.
As a result of both actions, property and interests in property of the designated individuals under US jurisdiction are blocked.
US persons are also generally prohibited from transacting with the named people.