Even beforeRussia invaded Ukraineon Feb. 24, Cogent Communications CEO Dave Schaeffer knew he had big problems.

The company determined that some of those attacks had traveled over Cogent’s system.

He began worrying about more-serious attacks that could target Ukraine, the US and the internet overall.

He fretted that Cogent’s data pipe could be a conduit for those attacks.

It was particularly important because Cogent is a giant, carrying about a quarter of the internet’s traffic.

Its fiber-optic cable connection stretches 100,000 miles and touches 51 countries.

Unplugging Russia is a big moment in the history of the internet.

Cogent’s action isn’t the only factor curtailing Russia’s online presence.

A host of companies headquartered in the West have made it difficult for Russians to use their services.

YouTube, for example,cut off ad revenue for Russian publishers.

Apple and Microsoft halted product sales, and Adobe shut down its cloud-based services for creative pros and advertisers.

Another international web connection provider,Lumen Technologies, ended its operations in Russia a few days after Cogent.

Russia also has taken actions that curtail the internet for its citizens.

It plans tocut off Instagram on March 14.

Twitter embraced thecensorship-evading Tor technologyafter Russia moved to block the service.

But he says improving global security was a more important consideration.

“We were afraid that the scale could change dramatically,” he said.

He sought input from across the company before making the decision and telling customers on March 3.

“I talked to some of our board members.

I talked to my management team.

I consulted with sales,” including staff in Ukraine, he said.

“Ultimately, listening to all sides, I felt that this was the right decision to make.”

The Russian embassy didn’t respond to a request for comment.

Though Ukraine has called for a complete Russian internet cutoff, internet advocates don’t like the idea.

The Internet Society is a nonprofit seeking to bring online access to everyone.

It turned down the Ukrainian request to cut off Russia.

Cogent, whose business is founded on a robust internet, doesn’t want a splinternet.

Cogent operates one of them.

“We have had to harden that router server multiple times due to attacks originating in Russia.

If you took down all 13, you would effectively render the internet useless within 12 hours.”