A serious security crisis in the northernmost corner of Europe would affect all of NATO. That is why the alliance just conducted the largest full-scale military exercise in decades — in Norway.

In October and November, some 50,000 soldiers from 31 countries were engaged in a major exercise designed to test our ability to operate together in crisis or war. Around 65 ships, 250 aircraft and as many as 10,000 vehicles took part. Exercise Trident Juncture 2018 demonstrated NATO’s revitalized focus on collective defense of its member states and the geopolitical importance of Europe’s northern flank.

Trident Juncture 2015 took place in the Mediterranean region. This year’s Trident Juncture was a unique opportunity for NATO and our partners Sweden and Finland to test and further develop our ability to operate together in the north. Norway’s rugged terrain, intricate coastline and demanding climate represent challenges in and of themselves to the war fighter, making this one of the reasons why it is so important to train here. Not just because it makes us better at defending ourselves, but also because it strengthens the bond between our countries and sends a strong signal to anyone who may want to use military power to force our will. The fact that 31 countries contributed to the exercise proves that we, as an alliance, stand together.

Even more importantly, the exercise demonstrated our will and determination to come to each other’s aid, should it ever be necessary. With Trident Juncture 2018, we have shown in a very visible way that we will come to the aid of any member nation, should any of us need it.

We see no military threat against Norway today. However, we have seen a more assertive Russia with both the will and the ability to use military power to achieve political goals. Cyberattacks and disinformation are fueling political polarization in both Europe and the United States, which in turn is challenging democratic institutions and our ability to compromise. International terrorism is changing how we think about security; migration has emerged as perhaps the No. 1 dividing force; and climate change is affecting all of these issues in ways we cannot fully predict.

As members of a successful alliance, we all share a common responsibility to maintain peace and stability in our neighborhoods — from the north to the south. Democracy, rule of law, freedom of speech and freedom of religion, as well as a rules-based world order, are at the heart of our nations. All 29 allies participated in exercise Trident Juncture. All 29 allies stand together in our 360-degree approach to security. And all 29 allies share the burdens of collective defense and deterrence. These are the fundamental values that make us capable of reacting to a rapidly changing security environment. We are firm believers in dialogue, transparency and a predictable world order based on international law and binding agreements.

Unfortunately, we see that these values are increasingly challenged. That is why it is necessary to have a credible military capability.

While Denmark, Norway and Iceland are members of NATO, Sweden and Finland are not. By including Sweden and Finland in a NATO exercise, we improve our ability to act together as neighbors.

The Nordic contribution to Exercise Trident Juncture was substantial, with over 13,000 soldiers and a large number of civilian personnel. In a fine example of Nordic cooperation, army elements from Finland operated as part of a Swedish brigade, and Danish helicopters supported the Norwegian brigade. NATO and partner forces from Finland and Sweden used military bases and airfields in all the Nordic countries, with the strategically important Iceland serving as a central hub, gateway and staging area for deployment and sustainment of allied forces across the north Atlantic.

From a Norwegian perspective, Trident Juncture 18 has been a success. For the first time in decades, the whole alliance came together in the High North to test reinforcement plans and to demonstrate that we are committed to collective defense. In addition, the sea lanes across the Atlantic are once again seen as vital.

Being a host nation, with all it entails, is a daunting task for a small nation like Norway. With this exercise, we were able to test our abilities to receive and accommodate allied forces. All units were in position, with their equipment, on time. All supplies were delivered as planned. The infrastructure was satisfactory. In addition, we were able to put our total defense concept to the test. More than 50 other Norwegian actors — governmental as well as nongovernmental — were involved.

Seen with Norwegian eyes, Exercise Trident Juncture 18 has contributed to continued stability in the High North.

Frank Bakke-Jensen is Norway’s defense minister.