• The U.S. Navy was "impacted" by Chinese state-backed hackers, Secretary of the Navy Carlos Del Toro told CNBC on Thursday.
• The infiltration, which targeted infrastructure in the U.S. and Guam, was disclosed Wednesday by Microsoft and by the National Security Agency along other intelligence agencies.
• Critical communications, maritime and transportation infrastructure were compromised, Microsoft warned.

The U.S. Navy has been hit by the Chinese state-sponsored hack that Microsoft disclosed Wednesday, Secretary of the Navy Carlos Del Toro told CNBC's Morgan Brennan on Thursday.

Del Toro said the U.S. Navy "has been impacted" by the cyberattacks, adding that it was "no surprise that China has been behaving in this manner, not just for the last couple years, but for decades."

He declined to provide further detail on the incursion but suggested that the Navy had been contending with cyberattacks like this for years.

Microsoft issued a warning Wednesday as did intelligence agencies including the National Security Agency, the Cybersecurity and Infrastructure Security Agency, and the cybersecurity agencies of four other nations. The warnings alerted corporate and public enterprises that a sophisticated Chinese state-backed hacking group had successfully exploited a vulnerability in a popular cybersecurity suite.

The vulnerability, which was exploited by a group codenamed "Volt Typhoon," affects critical cyber infrastructure across a range of industries, Microsoft said Wednesday. The company said the Chinese hackers had targeted communications and maritime sectors in Guam, which is home to a key U.S. military base.

The hacking group appears to have been focused on surveillance, rather than disruption, Microsoft said. But top intelligence officials and researchers expressed concern that Guam had been targeted, telling The New York Times that the island territory would be crucial to fending off a long-feared invasion of Taiwan by China.

The Chinese Foreign Ministry and state-controlled press dismissed the findings from Microsoft and the intelligence community as "disinformation."

Earlier Thursday, a State Department spokesperson said it is vital for both the government and the public to stay vigilant. "We will continue to work with our allies and partners to address this critical issue," spokesperson Matthew Miller said at a briefing.