Allies agreed at the Wales Summit in 2014 to implement the Readiness Action Plan (RAP) in order to respond swiftly to the fundamental changes in the security environment on NATO's borders and further afield.

Building on the RAP, Allies took further decisions at the Warsaw Summit in 2016 to strengthen NATO's deterrence and defence posture and to contribute to projecting stability and strengthening security outside of Alliance territory.

Together, these decisions are the biggest reinforcement of Alliance collective defence in a generation. Combined with the forces and capabilities required for rapid reinforcement by follow-on forces, these measures will enhance the security of all Allies and ensure protection of Alliance territory, populations, airspace and sea lines of communication, including across the Atlantic, against threats from wherever they arise.

At their meeting on Oct. 26, 2016, Allied defence ministers confirmed troop contributions to the four battalion-size battlegroups: Albania, Italy, Poland and Slovenia will contribute to the Canadian-led battlegroup in Latvia; Belgium, Croatia, France, Luxembourg, the Netherlands and Norway will join the German-led battlegroup in Lithuania; Denmark and France will contribute to the UK-led battlegroup in Estonia, and Romania and the United Kingdom will join the US-led battlegroup in Poland. Later on, Spain confirmed its contribution to the battlegroup in Latvia. Contributions will be made on a voluntary, sustainable and rotational basis.

Ministers also decided a number of tailored measures to increase NATO presence in the southeast of the Alliance on land, at sea and in the air with more multinational land training, combined joint enhanced training, more maritime activity and increased coordination.

More about the present structure.