The implementation of the peace agreement proved difficult.
The recent murders "are palpable, dramatic evidence of the risks and uncertainty that exists around the implementation of the peace accord," Santos said after the meeting.
To their credit, they had mobilized public support for the implementation of the peace accords with Egypt and lobbied for a withdrawal of Israeli forces from Lebanon.
"It is welcome news because it is a step forward in the implementation of the peace agreement," Machar said from Ethiopia.
Washington has long hoped that issues related to settler violence would vanish after the implementation of a peace deal.
For these and other reasons, allowing non-bloc settlers to remain in the West Bank might complicate the implementation of any peace agreement.
Representatives of the Organisation for Security and Cooperation in Europe, which is monitoring the implementation of the peace plan, were not present at the prisoner swap, said Medvedchuk, whose daughter's godfather is reportedly Vladimir Putin, the Russian president.
But the US said it wanted to see a renewed commitment to the implementation of the peace agreement and a "fundamental shift" in the relationship with the humanitarian community.
The British, French, Germans and Russians, who made up the remainder of the Contact Group for the negotiations, were aware they were there chiefly to make up the numbers and eventually to commit resources to the implementation of a peace agreement.
UN Secretary-General Ban Ki-moon urged the Security Council on Monday to impose an arms embargo on South Sudan, sanction leaders and commanders who are blocking the implementation of a peace deal and to fortify the UN peacekeeping mission.
