TARTU, Estonia (AP) — NATO nations and allies are battling malware in tablets and infected devices this week in the alliance’s largest cyber drill to date aimed at improving members’ data privacy in crisis situations.

Some 400 participants from 33 countries were focused on solving scenarios including attacks on high-ranking officers’ computer equipment during an exercise at a cyber range in Tartu, Estonia’s second-largest city.

“The idea is to replicate dynamics and threats that are real,” said Lt. Col. Christian Braccini, a researcher from the NATO cyber think tank and training center in the capital, Tallinn.

The five-day Cyber Coalition 2015 exercise, which ends Friday, included teams from non-NATO members Austria, Finland and Sweden, with Georgia, Japan and Jordan as observers.

It comes amid a flourish of NATO activity and recent visits by NATO Secretary-General Jens Stoltenberg to the region, where Nordic and Baltic countries have watched Russia’s increasing military presence in the Baltic Sea with increasing trepidation.

U.S. Navy Cmdr. Robert Hoar, head of the NATO drill on behalf of the Allied Command Operations, stressed the scenarios do not include attacking or defending. He says teams were given realistic “story lines” to solve, including cyberattacks on devices.

“The focus of the exercise is not competition, it’s collaboration,” Hoar told reporters.

Participating nations have at least one representative at the high-security cyber exercise range in Tartu, 190 kilometers (120 miles) southeast of Tallinn.

It’s the third time such an event was held in Estonia, one of the most wired and technologically advanced countries in the world. Estonia itself was targeted in 2007 by hackers in one of Europe’s first major organized cyberattacks.