(NewsNation) — More than a dozen airports around the nation temporarily lost control over their public website on Monday, meaning travelers could not access travel information.

The glitch was fixed and service was restored without causing a major disruption, but the concern is what could happen going forward knowing that American airport systems are vulnerable to such cyberattacks.

Most air travelers probably weren’t even aware of the cyberattack that caused the technical glitch because it didn’t affect air traffic control, takeoffs and landings or security operations.

Los Angeles International Airport in Los Angeles, LaGuardia in New York, Hartsfield-Jackson airport in Atlanta and O’Hare in Chicago are among the airports that were targeted in this attack.

A pro-Russian hacking group known as Killnet has claimed responsibility for the attack, the Washington Post reported.

It’s called “a distributed denial of service attack.” The hackers overwhelm airport websites with fake users and the websites can’t handle the sudden uptick in usage. So, the websites go offline and stop operating.

The nation’s cybersecurity and infrastructure security agency said it first started receiving reports of the cyberattack early Monday morning.

“My only concern here is that we may be entering a new phase of increased targeting in the U.S. that might include more serious incidents. Time will tell,” said John Hultquist, vice president for intelligence at Mandiant, an American cybersecurity firm.

One aviation expert said the Russians might consider the minor glitches they created to be major wins and they could cause greater harm if the cyberattacks keep happening.

“The air traffic control system could go down, you could have interference with communications. All that could result in something really bad,” said aviation expert Joe Schwieterman.

The same Russian group claimed responsibility for hacking several government websites last week, and there’s no way to determine when and if they plan to strike again,