He led the government delegation to the abortive London peace conference of 27 May 1991, which was intended to broker an end to the Ethiopian Civil War.
Other attendees included Isaias Afwerki who led the EPLF, Meles Zenawi the leader of the TPLF, and Lencho Letta the deputy secretary general of the Oromo Liberation Front.
Ostensibly, the conference was supposed to explore ways to set up a transitional government in Ethiopia, but it was overtaken by events before its formal start.
The talks had yet to get under way when Cohen received a message claiming that Lieutenant General Tesfaye Gebre Kidan, acting President of Ethiopia, had lost control of the government's remaining armed units and Addis Ababa was threatened with a complete breakdown of law and order.
To prevent uncontrolled destruction and looting, Cohen recommended that EPRDF forces immediately move into Addis Ababa and establish control.