The UK and its six allies have signed a memorandum of understanding (MoU) for the Joint Expeditionary Force (JEF), which will allow the countries to share armed forces' skills, resources and knowledge.
Britain will play a leading role in the JEF, which will include around 10,000 troops from Denmark, Estonia, Latvia, Lithuania, the Netherlands, and Norway.
According to the UK Ministry of Defence, the JEF will consist of a pool of high-readiness forces, which will be able to address emergencies using combat power, conventional deterrence, and humanitarian assistance.
Reportedly distinct from existing treaty organisations, the JEF is expected to complement other multinational intervention forces, and support the activities of the UN, Nato, and the EU.
The UK is expected to provide commando, airborne, armoured, aviation, air and maritime task groups.
UK Defence Secretary Michael Fallon said: "In a world of ever-greater uncertainty and growing threats it's right that the UK plays a leading role in developing this high-readiness force.
"Building on our pledges made at the Nato Summit, this demonstrates our commitment to crisis management and cooperative security.
"We are stronger together and have agreed to attach forces to the JEF when the time is right. The force will allow the UK and our allies to share knowledge, skills and resources, and will mean we can deliver a rapidly deployable, flexible and integrated joint force."