[1][2] It is the primary civilian intelligence agency of Sri Lanka and is responsible for both internal and external intelligence-gathering.

SIS is responsible for the collection of intelligence about threats from internal and external sources to be used in the formulation of government policies and strategies.

[citation needed] Under the Defence Secretary Gotabhaya Rajapaksa the intelligence agencies that were in desperate condition built-up a cohesive apparatus, which achieved significant success, including anti-LTTE operations overseas and the SIS played a huge role in the Fourth Ealam war.

[8][4] In January 2015 the director of the SIS, Chandra Wakista, resigned following the presidential election, amid allegations of phone tapping of opposition politicians.

[5] Kumaran Pathmanathan aka KP, who was involved in arms procurement for LTTE, was captured in Malaysia and moved to Sri Lanka via Thailand by this Agency.