On June 10 , 1970 , a major counter @-@ offensive was launched by the Portuguese army . The Gordian Knot Operation ( Portuguese : Operação Nó Górdio ) targeted permanent insurgent camps and the infiltration route across the Tanzanian border in the north of Mozambique over a period of seven months . The operation involved some 35 @,@ 000 Portuguese troops , particularly elite units like paratroopers , commandos , marines and naval fusiliers .