The principal functions of the department in 1991 were to defend the state against internal and external threats and, through the Philippine National Police, to maintain law and order.

In 2002, President Gloria Macapagal Arroyo won support from her Cabinet and the Congress for the deployment of American soldiers in the Philippines as part of the war on terrorism.

She convened a meeting of the NSC to pull wavering officials - including her Vice President, Teofisto Guingona Jr. - into line and smooth over differences in her administration over the issue.

[5] In 2016, the President Rodrigo Duterte convened the NSC and discussed his major initiatives: the war on illegal drugs, peace talks with communist and Moro rebels, and the territorial disputes with China.

The NSC's function is to advise the President with respect to the integration of domestic, foreign, and military policies relating to national security.

It also serves as the President's principal arm for coordinating these policies among various government departments and agencies in matters involving national security.

[8] In 1992, President Fidel Ramos reorganized the NSC to include the Secretaries of Science and Technology, Trade and Industry, Finance, and Environment and Natural Resources, and the Director-General of the National Economic and Development Authority.

[11] As of January 2025, the members are as follows: The NSC Executive Committee (EXECOM) reviews national security and defense problems and formulates positions or solutions for consideration by the council.