Sir – Monday’s peace deal between the government in Indonesia and the Free Aceh Movement stands in stark contrast to developments in Sri Lanka. In Sri Lanka, the assassination of the foreign minister, Lakshman Kadirgamar, calls into doubt the possibility of a similar breakthrough between the government and the Tamil Tigers.

The peace processes in both countries had gained momentum after the Boxing Day tsunami. Aid pouring into both countries forced the conflict parties to engage with each other to distribute food and medicine to survivors.

External mediators – Martti Ahtisaari’s initiative backed by the EU in Aceh, and the Norwegian government in Sri Lanka – offered their good offices to facilitate negotiations. Both conflicts had lasted for decades, and killed and wounded tens of thousands, mostly civilians. All sides had committed human rights violations, and attempts to settle the conflict had failed.

For all those similarities, Aceh seems to have achieved the peace agreement that still eludes Sri Lanka. Why?

One explanation lies in the disaster itself: Aceh was the worst hit of all regions
affected, the death toll in Indonesia being more than twice as high as in Sri Lanka.

Another explanation lies in the way in which governments and rebel leaders responded. The Indonesian government and Free Aceh Movement quickly used the opportunity created by international attention, aid and a new sense of priorities and began negotiating in earnest. In Sri Lanka, it took several weeks before the two sides even could agree on how aid was to be distributed.

In addition, in Sri Lanka the Tamil Tigers were split and one of their senior commanders had broken away from the movement. The president of Sri Lanka, only a month before the tsunami struck, had won an election showdown with her more compromise-willing prime minister after a public disagreement over where the peace process should go.

In Indonesia, meanwhile, Susilo Bambang Yudhoyono, a retired general, had won the presidential elections in September 2004. The day after the disaster, the exgeneral, who has by no means an unblemished record in terms of respect for human rights, ordered the Indonesian security forces to halt all offensive operations against insurgents in Aceh and to focus on humanitarian operations in the province. Eventually, the Free Aceh Movement followed suit.

Two conclusions can be drawn. International assistance is vital for peace agreements, but ultimately local leaders need to negotiate them. In Indonesia, government and former rebel leaders have proved worthy of international support – without it, chances of lasting peace would be unfairly diminished.

Professor Stefan Wolff, University of Bath