Civilian air-traffic computer networks have been penetrated multiple times in recent years, including an attack that partially shut down air-traffic data systems in Alaska, according to a government report.

The report, which was released by the Transportation Department's inspector general Wednesday, warned that the Federal Aviation Administration's modernization efforts are introducing new vulnerabilities that could increase the risk of cyberattacks on air-traffic control systems.

The FAA is slated to spend approximately $20 billion to upgrade its air-traffic control system over the next 15 years.

The increasing reliance of modernized systems on the Internet "is especially worrisome at a time when the nation is facing increased threats from sophisticated nation-state sponsored cyber attacks," wrote Assistant Inspector General Rebecca Leng.

"We are working on developing security architecture for that whole system," said FAA spokeswoman Laura Brown. "We have identified it as an issue we need to focus some attention on, and we're doing that."

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