The JEF is governed by a Comprehensive Memorandum of Understanding rather than a legal treaty, which allows an ‘opt-in’ approach rather than one demanding consensus. The JEF only requires the Framework Nation plus one other country to conduct JEF activity. This means JEF is flexible, agile, and can react rapidly during any crisis.
Since the illegal and unprovoked attack by Russia on Ukraine in February 2022, the JEF has exponentially increased activities across its Area of Interest. These activities have ranged from tactical unit level observation teams, through to multi-national exercises and operations, and strategic ministerial level table-top exercises. Furthermore, the JEF has gone through a period of ‘operationalisation’ by developing a catalogue of JEF Response Options (JROs) – the protocols by which JEF can respond in times of crisis.
In 2023, the JEF activated a JRO for the first time. It was focused on Critical Undersea Infrastructure (CUI) protection in the Baltic Sea Region, in response to the damaged caused to the Baltic Connector natural gas pipeline between Finland and Estonia. The following year, the JEF activated ‘NORDIC WARDEN’ which brought all ten JEF Participant Nations together to proactively protect CUI, monitor shipping, and respond to hybrid threats. The operation integrated advanced maritime awareness tools and coordinated intelligence sharing with NATO, demonstrating the JEF’s ability to deliver independent effect and adapt to evolving security challenges.
In 2025, JEF conducted its most ambitious live activity since it was created in 2014. Exercise TARASSIS was a large scale, multinational and multi-domain rehearsal of JROs covering JEF’s whole Area of Interest.
In addition to JRO activations, the JEF Activity Programme plays a key role. At its core is the JEF LION series of exercises, which serves as the framework for end-to-end force development and interoperability across the JEF. The LION series run on a three-year cycle and consists of live multi-domain activities and command post exercises designed to enable, rehearse, demonstrate and confirm the JEF’s ability to operate as a coherent, integrated and responsive force. The series consists of LION PROTECTOR, LION SENTINEL and LION SHIELD.
JEF+
team taking part in TARASSIS, Latvia 2025.
The JEF can conduct operational or exercise activity with non-JEF entities under the banner of JEF+. The JEF+ approach provides a flexible framework for collaboration with like-minded partners beyond the JEF membership, enabling them to participate in selected activities where interests align. Examples include exercising with the United States in GLOBAL GUARDIAN and Canada’s involvement in TARASSIS, demonstrating how JEF+ strengthens interoperability, enhances readiness, and broadens cooperation with key partners.
JEF-Ukraine Enhanced Partnership
Recognising Ukraine’s importance to regional security, the JEF established an ‘Enhanced Partnership’ with Ukraine in 2025 to deepen cooperation.
event in Sweden.
The partnership allows Ukraine to participate in JEF activities, planning, and operational meetings. This creates an invaluable mechanism for lessons sharing to increase JEF capabilities as well as providing a valuable platform for channelling multi-lateral support to Ukraine from JEF Participant Nations.