The Treasury Department said it targeted Salim and Ali Kony.
The United States announced sanctions Tuesday against the sons of Joseph Kony, leader of the central Africa-based Lord’s Resistance Army rebel group.
The Treasury Department said it targeted Salim and Ali Kony "for acting for or on behalf of the LRA and/or Joseph Kony."
The move follows sanctions launched against Joseph Kony in March "for engaging in the targeting of civilians in the Central African Republic through the commission of acts of violence, abduction and forced displacement," it added.
The LRA, which emerged in northern Uganda in 1987, acquired a fearsome reputation because of its brutal activities in northern Uganda, South Sudan, the Democratic Republic of Congo and the CAR.
The group has killed more than 100,000 people and kidnapped more than 60,000 children, forcing many of them to become child soldiers, the UN says.
Charged with war crimes by the International Criminal Court in The Hague, Joseph Kony remains at large.
Tuesday’s action freezes any assets belonging to his sons within US jurisdiction and bars Americans from engaging in business with them, the Treasury Department said.
The move "targets the finances of the LRA and its leaders, while also combating their participation in the global illicit ivory trade," Treasury added, calling it "the latest in a collaborative international effort to address the widespread violence in the Central African Republic."
The LRA has moved freely across porous regional borders, crossing in 2008 into the CAR, where a 2013 coup prompted ethnic and religious clashes that claimed thousands of lives and displaced about a quarter of the population.
Combining religious mysticism with guerrilla tactics and bloodthirsty ferocity, Joseph Kony has turned scores of young girls into his personal sex slaves while claiming to be fighting to impose the Bible’s Ten Commandments.
Salim and Ali Kony, part of the LRA’s leadership since 2010, are among its senior officers, the Treasury Department said, adding that Ali, a potential successor to his father, is "predominantly involved in LRA operational planning and its intelligence apparatus."
Salim heads most of the LRA’s field operations and manages the group’s financial and logistical networks.
"Salim and Ali have been jointly responsible for enforcing discipline within the LRA, and Salim is reported to have killed LRA members who intended to defect," the statement said.
Although weakened by the capture or defection of several commanders, the LRA has been stepping up attacks in the CAR, expanding into new areas and abducting more children, according to the United Nations.
Some 2,000 Ugandan soldiers backed by US troops are currently deployed in eastern CAR as part of an African Union mission to tackle the LRA rebels, on top of another 10,000 UN troops stationed in the country.