An embargo and sanctions against South Sudan fighters are regularly discussed at the United Nations, and in Washington and Europe.
But there has been little real action, with the White House seen as dragging its feet after making a strong push for the independence of the world's youngest nation in 2011.
"I would characterise Kerry's view as supporting the State Department's view in support of a UN-led embargo," a U S administration official told AFP yesterday.
Rice does not see a benefit to an embargo that would only hit the elected regime of President Salva Kiir and not the rebellion of his former vice president Riek Machar, according to Foreign Policy.
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The US official refused to discuss any possible disagreement between the White House and the State Department on the issue.
In the months that followed the start of the conflict in December 2013, US President Barack Obama repeatedly condemned, pressured and threatened sanctions. He also sent Kerry on a peace mission to Juba.
Kiir and Machar signed yet another ceasefire agreement late on Sunday following four days of talks in Ethiopia, but they did not address the core issues behind the 13 months of fighting.
The United States has fought for the cause of South Sudan for the past three decades, from backing John Garang's 1983-2005 rebellion to the July 2011 independence ceremony attended by Rice in Juba.