Russia is hacking into the smartphones of NATO troops — including US troops — in an effort to get more information about the plans of the alliance. It’s the latest example of Russia’s increasingly confrontational stance against the West.

The Wall Street Journal, citing NATO troops and officials, reported on Wednesday that Russia had compromised the smartphones of some of the 4,000 NATO troops that have been in Poland and the Baltics since June to deter more aggressive Russian actions in the region. Russia also uses surveillance drones to access information on the phones, according to the report.

US Army Lt. Col. Christopher L’Heureux, who leads the NATO base in Poland, described what happened to him, telling the Journal that after a shooting drill he found evidence that somebody with Russian IP address tried to access his phone. “They were geolocating me, whoever it was,” he said. “I was like, ‘What the heck is this?’”

He wasn’t the only target. At least six other soldiers under L’Heureux’s command were also hacked. And in March, an Estonian soldier experienced similarly bizarre interference on his cellphone: hip-hop music he hadn’t even downloaded randomly started playing on his device (Estonia is a NATO member).

The Russian Defense Ministry did not respond to the Journal’s request for comment, and the Russian Embassy did not immediately respond to Vox’s request for comment.

Russia is really, really worried about NATO troops near its borders

Vladimir Putin, Russia’s longtime leader, is not a big NATO fan. After all, NATO was created back in 1949 explicitly to check the Soviet Union’s military power. And while the Soviet Union is no more, Russia still sees NATO as one of its biggest threats.

“NATO remains a military alliance, and we are against having a military alliance making itself at home right in our own backyard or in our historic territory,” Putin said in 2014 after Russia invaded Crimea.

Since then, NATO has taken an even stronger stand against Russian aggression, in particular by putting more troops in Poland and the Baltics. Clearly, Russia is rattled by this.

From September 14 to 20, the Russian and Belarusian militaries held a joint war game to simulate fending off an attack from Western powers — in other words, NATO. Hacking the personal cellphones of NATO troops is just more evidence of how seriously Russia views the NATO threat.

“Russia has always sought to target NATO servicemen for intelligence exploitation,” Keir Giles, an associate fellow at Chatham House’s Russia and Eurasia Program, told the Journal. “But such a campaign of harassment and intimidation is unprecedented in recent times.”