LAS VEGAS — American intelligence officials lack evidence that leaks from former National Security Agency contractor Edward Snowden are behind the Russian and Chinese governments’ heavy crackdowns on U.S. tech giants.

A former high-ranking American intelligence official told VentureBeat late Thursday that U.S. intelligence believes the Snowden leaks — regarding the infiltration of Microsoft, Yahoo, and others by the NSA — are behind the Russian and Chinese backlash. But, the source said, plenty of questions remained unanswered — and so far there’s no proof of a connection.

In the meantime, these nations are pressuring U.S. tech companies, for instance with aggressive antitrust investigations in China.

“The fact there’s been a push (in Russia and China) to get American corporations off the playing field is suspicious. If you look at what’s happening, the timing is odd that those governments are pushing hard,” against American IT firms, the former intelligence official said.

“It makes one wonder. But we just don’t know.”

Snowden was on more than a few people’s minds at the Black Hat conference here this week. Many assume that the leaks have done enormous damage to the U.S. tech industry’s international standing.

Indeed, at a workshop hosted by the Electronic Frontier Foundation’s Mark M. Jaycox and former National Security Council member J. Michael Allen about NSA meta data collections efforts, the two men spoke at length about the damage done to American IT companies in the wake of Snowden’s document dumping.

“The impact is there,” Jaycox told a crowd of 500 people gathered in a ballroom at the Mandalay Bay hotel.

To be sure, many here at Black Hat outright support Snowden and his document leaks. They consider him the poster child for all that is wrong with the NSA and a much-needed whistleblower who helped expose the illegal practices of America’s biggest and most powerful spy agency.

Beijing recently launched an aggressive antitrust campaign against Microsoft, raiding its offices in four Chinese cities and seizing computers and files. On Monday, China warned Microsoft not to interfere in its investigations. Beijing accuses Microsoft of failing to share or release documents for its Windows OS and Office software suites.

Snowden’s documents revealed the NSA’s massive infiltration of Microsoft’s OS and other products for spying purposes. The Communist-controlled press has been banging drums, saying they believe Microsoft products are being used to spy on the country. China is a huge market for Microsoft, Apple, Google, and others.

In Russia, president Vladimir Putin has also come down heavy on U.S. tech companies named in Snowden’s NSA documents.

Both countries have spent heavily on monitoring tools and software to surveil their own people.

When Snowden fled the States last year, he went first to Hong Kong and then to Russia. Former NSA and CIA director Michael Hayden told VentureBeat in May, “I would lose all respect for the Russian and Chinese security services if they haven’t full exploited everything Snowden had to give.”

U.S. intelligence strongly believes Snowden gave the Chinese and Russians information on how the NSA was using U.S. tech firms to spy on those countries. And some believe there’s no way the Chinese and Russian security services would have first let him travel through and then settle down in those countries if he didn’t proffer information.

Over at Black Hat, the speakers at the talk on NSA metadata collection efforts said the aftereffects of the revelations have hurt American IT operators like Cisco and Microsoft and have impacted the reputations of others. U.S. IT firms pulled in more than $1 trillion for the U.S. economy in 2013, much of that abroad, according to figures from the Consumer Electronics Association.

In the end, speculation is all that the U.S. intelligence community has right now about whether Snowden’s information is leading to the crackdowns in China and Russia. But certainly the timing of the Microsoft raids in China is keeping American spies on their toes.

“It is, right now, a big unknown,” another former intelligence official told VentureBeat.