Google’s brief outage on Monday saw some of its internet traffic mistakenly rerouted through networks in Russia, China and Nigeria, according to one report.

The outage put “valuable Google traffic in the hands of ISPs in countries with a long history of Internet surveillance,” wrote Ameet Naik, a technical marketing manager at ThousandEyes, in a blog post.

For starters, internet traffic to Google got dropped at China Telecom. “Why would traffic from a San Francisco office traversing to Google go all the way to China?” he wrote. “We also noticed a Russian ISP in the traffic path, which definitely sparked some concerns.”

Unfortunately, incorrect routing instructions sent some traffic to the Russian network operator TransTelekom, as well as China Telecom and Nigerian provider MainOne, Naik wrote.

“This incident at a minimum caused a massive denial of service to G Suite and Google Search,” he wrote.

It also “underscores” a weakness of the Internet.

Google resolved the issue on Tuesday. The company wrote in the Google Cloud Platform performance report that it believes the root cause of the issue was external, and the company plans to conduct an internal investigation to make the appropriate improvements to the system.

Google told The Wall Street Journal that the incident did not compromise any data. Evidently, network-based attacks can send data off course. The attacks are possible because exchange traffic through a system is mostly based on mutual trust through protocols that are nearly as old as the internet itself.