Hackers behind a series of destructive, financially motivated cyberattacks against some of the U.K.’s largest retailers are now going after big American brands, Google said Wednesday.

“Major American retailers have already been targeted,” John Hultquist, the chief analyst for Google’s Threat Intelligence Group, told NBC News.

At least three top British retailers have experienced cyberattacks in recent weeks. Marks & Spencer was forced to pause online orders for weeks. Hackers who contacted the BBC provided evidence of “huge amounts of customer and employee data” stolen from the Co-op Group. The third, Harrods, restricted some internet access at store locations, though a spokesperson told NBC News that it has not seen evidence that customer data was stolen.

Hultquist declined to name which American retailers the hackers may be going after.

The National Retail Federation, which represents thousands of companies including Walmart and Target, acknowledged the threat.

"U.S.-based retailers are aware of the threats posted by cybercriminal groups that have recently attacked several major retailers in the United Kingdom, and many companies have taken steps to harden themselves against these criminal groups’ tactics over the past two years,” Christian Beckner, the NRF's vice president of retail technology and cybersecurity, told NBC News in a statement.

As one of the world’s largest tech companies, Google sells services like cloud storage, networking and security protections to some of the biggest retailers in the world, providing it significant insight into how hackers operate.

It’s not yet clear if there is a technical reason for the hackers to target retail companies, such as a vulnerability in a shared industry software program.