Seoul says North Korea has doubled hacking efforts

South Korea on Friday said North Korea has doubled its cyberattacks targeting the South over the past month.

During a parliamentary committee meeting, South Korea’s National Intelligence Service (NIS) told lawmakers that its neighbor had unsuccessfully tried to infiltrate the country’s railway control system, as well as numerous financial institutions, The Associated Press reported.

The intelligence agency also fleshed out recent reports that North Korea was trying to crack into South Korean government websites and smartphones.

Officials said Pyongyang had targeted 300 smartphones belonging to foreign affairs, security and military personnel.

Hackers successfully infiltrated 40 of these phones, pilfering text messages, voicemails and phone logs, according to the office of a South Korean lawmaker.

The intelligence agency did not tell lawmakers whether any of the data stolen was sensitive material.

The escalating North Korean cyber campaign comes amid heightened tensions between the two neighbors.

Pyongyang on Monday threatened to launch a preemptive nuclear strike on South Korea and the U.S. in response to joint U.S.-South Korea military exercises taking place this week.

The efforts also fit an emerging pattern for North Korea, in which Pyongyang ties cyber campaigns to moments of blustery rhetoric and military drills.

In January, shortly after Pyongyang officials claimed to have conducted a successful hydrogen bomb test, Seoul said it believed North Korea had launched a spate of cyberattacks on southern targets. Reportedly the digital assaults planted malware on a number of government networks.

U.S. lawmakers recently approved a bill that slaps sanctions on North Korea for its burgeoning cyber capabilities and resurgent nuclear program.

“This is the first time we’ve ever had mandatory sanctions on cyberattacks,” Sen. Cory Gardner (R-Colo.), who backed the legislation, told The Hill last month. “It’s long overdue.”

“This will be a model for what we do as other bad actors try to attack the United States through cyber means,” added Gardner, who chairs the Senate Foreign Relations Subcommittee on East Asia, the Pacific and International Cybersecurity.