The Tonga Defense Service (TDS) is a 400-person force. The force is comprised of a headquarters platoon and a light infantry company. A coastal naval unit of four small patrol boats and amphibious landing craft operate as a component of the TDS. The force's mission is to assist in maintenance of public order, to patrol coastal waters and fishing zones, and to engage in civic action and national development projects. The main base of operations is the capital, Nuku'alofa.

The TDS is partially supported by defense cooperation agreements with both Australia and New Zealand, which support the TDS with small in-country detachments of military technicians. The United States military provides training to the TDS and conducts humanitarian civic action projects in Tonga. In 2002, TDS soldiers were deployed as part of a multi-national regional peacekeeping force in the Solomon Islands.