Cross-border ground raids by state-backed security forces can have a detrimental impact on guerrillas' ability to wage war. External support in neighboring countries can be an important source of strength to insurgent forces. However, cross-border raids and their security gains come at a political cost. This thesis examines the conflicts in Malaya (1946a "1950), Nicaragua (1981a "1990), Algeria (1954a "1962), Namibia (1960a "1989), South Vietnam (1960a "1975), and Afghanistan (1978a "1992) to identify operational and strategic-level considerations in planning cross-border operations to reduce the political costs of such operations. The study examines the relationship between security gains and political costs, including subsets of factors intrinsic to both variables. The research presents lessons applicable to the contemporary counterterrorism environment and suggests how military and political counterinsurgents can combine lines of effort in conducting cross-border operations against external insurgent sanctuaries."