Along with many other Sri Lankan observers, I have watched recent events unfold in the country in disbelief, horror and despair.

Cornered in a shrinking conflict zone in the north-east of the country, with little access to food, water or medicine since the beginning of this year, nearly 100,000 civilians have been the worst casualty of this fighting, which promises to reach its bloody denouement soon. Tamil civilians have paid a heavy price for their conflict, and their misery has largely been ignored.

Sure, the UN has issued strong statements and concerned governments have routinely expressed their outrage. But the response of the international community so far has lacked collective will.

With both the government and the Tamil Tigers violating the rules of war, an urgent and combined response is vital. The UN Security Council needs to act urgently to protect civilians; influential countries – such as Sri Lanka's largest bilateral donor, Japan, and neighbouring India – need to put pressure on a government heady with military success.

The end of the organised LTTE does not guarantee the end of terrorism in Sri Lanka, as continuing militant strikes suggest.

And the process brokered by Norway that led to a ceasefire agreement in 2002 seems truly dead. Only a new process, built on different foundations, has any chance of bringing sustainable peace. For now, President Mahinda Rajapakse's attempts at a negotiated settlement with the minority Tamil community have been dismissed by even the moderate Tamil leadership. The Sri Lankan government's "liberation" of the eastern provinces – a model they seek to replicate for the north – does not inspire confidence.

Daily killings, extortion and disappearances are a fact of life in the restive Batticaloa district. The government still has not devolved power to the Eastern Province, as promised in 1987 in response to demands for regional autonomy. After decades of brutal conflict, the government's desperate bid for the end game is understandable. But justice and pragmatism require a package of constitutional reforms that will offer Tamils real rights and an effective share in power. Until that happens, victory in the battlefield will remain hollow; an aggrieved minority at home and an embittered diaspora abroad will ensure that peace remains elusive in Sri Lanka.

Charu Lata Hogg is an Associate Fellow in Chatham House's Asia Programme