At this point he obtained a student visa for the United States and left Ethiopia to continue his education and to avoid the violence brought about by the military dictatorship known as the Derg.

In 2013–14, he was the mediator in the conflict between the Government of the Republic of South Sudan and an insurgency movement called the South Sudan Democratic Movement/Army that led to a two-part peace agreement: a cease fire and cessation of hostilities agreement in January 2014, followed by a comprehensive peace accord in May 2014 which aimed to address the political, economic, social, military and security issues and interests of the warring parties underlying the conflict.

[5] He has also been involved as a facilitator in grassroots peacebuilding and reconciliation initiatives in Ghana, Nigeria, Sierra Leone, Liberia, Kenya, South Africa, Sri Lanka, Afghanistan, Colombia, and Guatemala.

[6] In 2008 Assefa was invited to join the mediation team working to stop the post-election violence in Kenya and create a power-sharing government by former secretary general of the United Nations, Kofi Annan.

Other team members included former president of Tanzania, Benjamin Mkapa, and the former first lady of Mozambique and of South Africa, Graça Machel.