The Latest on congressional hearings on social media issues (all times local):
Sen. Mark Warner of Virginia is blasting Google for a response to lawmakers' inquiries about its reported plans to launch a search engine in China that would comply with censorship laws.
Warner says he is "truly disappointed" with a letter from Google CEO Sundar Pichai that arrived Friday, before a Senate hearing Wednesday in which Google will not have a representative present.
Pichai said in the letter he wasn't able to answer detailed questions and said the question of whether it would release a search engine in China "remains unclear."
Warner says any Google effort to get back into China could help the Chinese government repress its citizens. Google says despite pulling its search engine from China in 2010, it still employs hundreds of workers there.
A nonprofit watchdog group says it bought ads on Google as recently as June while posing as the Russia propaganda agency that sought to influence the 2016 U.S. election.
The ads pointed to websites tied to Russia's Internet Research Agency, used rubles, and used the agency's tax ID.
The Campaign For Accountability says in a report published Tuesday that the ads were approved in as little as 24 hours. The campaign says the quick approval shows that Google is not doing enough to stop bad actors from abusing its platforms.
Google has accused rival Oracle and groups it works with of performing a stunt to impersonate Russian trolls. It says it has since disabled those accounts and has taken further action to upgrade its vetting process.
Google won't have an executive testifying alongside Twitter and Facebook before a Senate intelligence committee hearing Wednesday.
The committee invited Larry Page, the CEO of Google's parent company Alphabet. Google offered another executive instead, and the committee said no.
The other executive is chief legal officer and senior vice president of global affairs Kent Walker. Google says Walker will still submit testimony and brief members on the subject of the hearing, which is foreign influence operations and their use of social media platforms.
Walker's written testimony says the company found "limited activity" around government-backed election interference following the 2016 vote and took "swift action" once it did. Google says it continues to use "advanced technologies" to increase security and fight manipulation on its platforms.
Facebook's Sheryl Sandberg says the company is getting better at finding and combating adversaries who try to use the platform.
The company's No. 2 executive says in prepared testimony ahead of a Senate intelligence committee hearing Wednesday that those adversaries include financially motivated troll farms and "sophisticated military intelligence operations."
The Menlo Park, California-based company revealed last year that a Russian internet agency had used the platform to try to influence the 2016 U.S. presidential election. Earlier this year, special counsel Robert Mueller indicted 13 Russians behind the social media effort.
Sandberg says in the testimony that Facebook regularly looks for and discloses state-sponsored threats to law enforcement but does not make the details of these reviews public for security reasons.
Twitter's CEO says the company isn't biased against Republicans or Democrats and is working on ways to ensure that debate is healthier on its platform.
In prepared testimony released before a congressional hearing Wednesday, Jack Dorsey says he wants to be clear about one thing: "Twitter does not use political ideology to make any decisions, whether related to ranking content on our service or how we enforce our rules."
The testimony comes as some Republicans say conservatives have been censored on social media.
Dorsey offered an explanation of how San Francisco-based Twitter uses "behavioral signals," such as the way accounts interact and behave on the service. Those signals can help weed out spam and abuse.
He says such behavioral analysis "does not consider in any way political views or ideology."