The constitution of Sri Lanka, in no way states that Sri Lanka is to be made a sacred state for Buddha, whatever it may mean. In fact there is strict separation of church and state, as guaranteed in the constitution of Sri Lanka.
The violence in Sri Lanka is caused by Tamil separatists who are attempting to create a separate state in Sri Lanka by resorting to terrorism. The problems have absolutely nothing to do with religion.
Sri Lanka is a multi-ethnic, multi-religious, democratic nation that has existed in peace and harmony for centuries. The vast majority of the people in Sri Lanka are opposed to separatism. Hence the separatists are hoping to achieve by terrorism what they cannot by democracy.
The Sri Lankan Tamil terrorists, like terrorists the world over, do not respect age, sex or religious affiliation of their victims. The Sri Lankan government has the moral obligation to defend Sri Lanka against terrorism, whatever the age, sex or religious affiliation of the terrorists, even if it includes being cloaked in priestly garb.