Assistant Secretary of State for African Affairs Linda Thomas-Greenfield said that the United States was invoking the Child Soldiers Protection Act in sanctioning Rwanda, as Washington seeks to end "any involvement in the recruitment of child soldiers."
The sanctions were linked to actions by the M23, a group of former rebels who were integrated in the army in 2009 but mutinied last year.
"We will continue to have discussions with the Rwandan government on that issue," Thomas-Greenfield said.
In April 2012, the M23 turned their guns on their former comrades and launched the latest rebellion to ravage DR Congo's mineral-rich and conflict-prone east.
The United Nations accuses Rwanda of backing the M23, a charge the country has adamantly denied.
The UN and various rights groups have accused the M23 of atrocities, including rape and murder, in addition to the use of child soldiers, in a conflict that has caused tens of thousands of refugees to flee.