The Joint Expeditionary Force (Maritime) (or JEF(M)) (formerly the Response Force Task Group (RFTG), and prior to that the Joint Rapid Reaction Force (JRRF)), is the Royal Navy's contribution to the Joint Expeditionary Force (JEF) maintained at very high-readiness and available at short notice to respond to unexpected global events. In addition to the Royal Navy and the Royal Marines, the JEF(M) also includes elements of the British Army and the Royal Air Force. While it is primarily poised to conduct war-fighting or strike operations, the JEF(M) is capable of undertaking a diverse range of activities such as evacuation operations, disaster relief or humanitarian aid.

The Joint Rapid Reaction Force (JRRF) was a capability concept of the British Armed Forces from 1999 to 2010. It was a pool of specialised units from all three armed services tasked with rapid deployment worldwide at short notice. The force was intended to be capable of mounting operations up to medium scale warfighting. It could be employed nationally, or multinationally under the auspices of NATO, the United Nations or any other coalition.