GOTLAND — NATO conducted a war game exercise on the Swedish island of Gotland that simulated Sweden facing a threat from an unnamed country building up troops along the alliance's eastern border. The scenario tested members' actions before invoking Article 5 by simulating power outages and food shortages on Gotland caused by sabotage.

U.S. forces participated in the exercise, along with Ukrainian forces, who joined despite Ukraine not being a NATO member to advise on drone warfare and demonstrate battlefield experience. "In theory, it could happen tomorrow," said Rear Adm. Jonas Wikström, director of the exercise.

The exercise focused on Gotland because of its strategic location in the Baltic Sea between the Russian exclave of Kaliningrad, where Moscow has stationed missiles, and mainland Sweden. After the Cold War, Sweden ended its military presence on the island, then strengthened its forces there following Russia's full-scale invasion of Ukraine in 2022. Sweden and Finland decided to join NATO in 2024.

"If you control Gotland, you pretty much control the central part of the Baltic Sea," said Gen. Michael Claesson, chief of defense of Sweden. "A very reasonable scenario is that Russian President Vladimir Putin could use Gotland to test NATO by trying to take a thin sliver of alliance territory to probe the collective reaction," Claesson said.

Russia has carried out sabotage including cyberattacks against critical infrastructure and disinformation campaigns against countries across Europe for months. During the exercise, a group of Nordic and Baltic nations, the United Kingdom and the Netherlands announced a "hybrid navy." "Everything that offers European allies freedom of action is good," Claesson said.

Ukrainian drone pilots embedded with the exercise offered assessments of the participating forces' readiness. One pilot, identified as Tarik, described shortcomings observed during the training. "They stopped the training three times for troops to work out what to do better, but if it were real life they would have been dead," Tarik said.