An initial version of this article incorrectly referred to the possible target of an electronic disruption that also affected cellphone service in Western Latvia. It is Sweden’s Öland Island, not Finland’s Aland Islands.

Troops take part in joint Russian-Belarusian military exercises near the town of Borisov, Belarus, on Sept. 20, 2017. (Sergei Gapon/AFP/Getty Images)

Latvia's intelligence services are examining a partial disruption of the nation's cellular network and emergency-services hotline that may have been a fresh example of Russia's ­electronic-warfare capabilities, Latvian and NATO officials said.

The break in cellphone service in western Latvia and the 16-hour outage of the country's equivalent of 911 came around the time of recent major Russian military exercises that were a powerful demonstration of the Kremlin's ability to wage modern war.

If confirmed as attacks, the electronic breakdowns would show another capability in the Kremlin's arsenal — not just the reborn, muscular tank army and the accurate long-range missiles that were on display during the "Zapad" exercises, but also the capacity to disrupt civilian communications remotely. Such a tool could severely hamper Western authorities' ability to organize a quick civilian response in case of war. NATO officials already are concerned that Russia's potent antiaircraft missile technology gives the Kremlin effective control of most of Baltic airspace if there were a conflict.

Latvian Foreign Minister Edgars Rinkevics said authorities do not believe their country was directly targeted in the Aug. 30 incident that disrupted cellular service in the western Kurzeme region for seven hours. Instead, he said, Latvia may have been in the path of a broader electronic disruption directed at Sweden’s Öland Island. NATO officials said that Russia possesses electronic-warfare assets in its Baltic exclave of Kaliningrad and that at least one ship with that technology was in the Baltic Sea during the war games.

“Our authorities are analyzing a pattern of communications disruption that appears to have originated during the Zapad exercise against Öland Island, with some direct impact to Latvia,” Rinkevics said.

The island is located in a key spot in the Baltic Sea. Sweden, which is not a member of NATO, held major military exercises last month that included the participation of U.S. forces.

Rinkevics said Latvian authorities also are examining possible Russian involvement in a Sept. 13 outage of Latvia’s emergency phone hotline. Nothing has yet been proved, he said.

Spokesmen for the Swedish Defense Ministry and the Swedish Armed Forces said they were not aware of any cellular disruption on their territory at the time of the incidents in Latvia.

Officials also are looking at other explanations for the outages, which one characterized as not posing a major security threat.

During the Zapad exercises, which ended Sept. 20, “there were some unusual things going on,” Rinkevics said. “It hasn’t happened since the end of the exercises. It didn’t happen three months ago. I wonder why.” He said that the Latvian foreign ministry has not formally complained to its Russian counterpart because the intelligence services have not yet made a conclusive assessment.

Two other senior NATO officials, speaking on the condition of anonymity to discuss preliminary assessments of the exercises, echoed the Latvian concerns while also cautioning that Western intelligence services have yet to reach conclusions. A third senior NATO official said the alliance believes Russia used jamming technology and drones during the exercises that it has also used in Ukraine and Syria.

The Russian Defense Ministry did not respond to a request for comment.

Sept. 14 was the officially declared start of the joint exercises in Belarus and Russia's western regions, but senior NATO diplomats said military activity intensified weeks before. NATO leaders say Russian military planners evaded transparency requirements by claiming that a single major exercise was actually a series of smaller ones that fell below reporting levels designated by international agreements. The Kremlin denies the accusation.

NATO allies watched the exercises carefully to learn more about the Russian military’s modernization efforts — and also to guard against any possible incursion into allied territory. In the end, allied officials say, between 40,000 and 60,000 troops participated in the exercises, well above the 13,000 threshold that triggers transparency requirements.

“This was a demonstration of muscle. This was not defensive but offensive,” Rinkevics said, echoing the broader Baltic and NATO assessment.

The U.S. Army’s senior commander in Europe, Lt. Gen. Ben Hodges, said Russia has been honing its cyberwarfare capabilities since the 2014 annexation of Ukraine’s Crimean Peninsula. It has used electronic blocking and jamming techniques against the Ukrainian military, which has fought Russian-backed forces in eastern Ukraine since shortly after Russia took Crimea.

“They’ve put on display a significant electronic-warfare capability that is powerful, sophisticated,” Hodges told reporters in Brussels. “A lot of this was on display during the exercise.”

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