He has also been praised for his role in brokering the 2005 peace agreement between the separatist Free Aceh Movement and the Indonesian government that ended nearly 30 years of fighting. In addition, he was involved in efforts to end the conflict in Northern Ireland.
Ahtisaari, ayrılıkçı Özgür Aceh Hareketi ile Endonezya hükümeti arasındaki yaklaşık 30 yıllık savaşı sona erdiren 2005 barış anlaşmasındaki arabuluculuk rolünden ötürü de övgü aldı.