(Reuters) - A major armed ethnic group in southeast Myanmar vowed on Tuesday to defend its territory from what it said were thousands of government troops advancing “from all fronts” and urged the international community and neighbour Thailand to protect its people. In a statement, the Karen National Union (KNU), the country’s oldest ethnic army, asked the international community to provide humanitarian help as its people flee fighting and to pressure the ruling military to cease using weapons on civilians. It said the world should sever economic and military ties with Myanmar’s junta.