When David North, the editorial chairman of the World Socialist Web Site, noticed a drop in the site's traffic in April, he initially chalked it up to news fatigue. But when he dug into the numbers, Mr. North said, he found a clearer explanation: Google had stopped redirecting search queries to the site. He discovered that the top search terms that once brought people to the World Socialist Web Site were now coming up empty. Accusations that Google has tampered with search results are not uncommon. But they are taking on new life amid concerns that technology behemoths are directly - or indirectly - censoring controversial subjects in their response to concerns over so-called fake news. In April, Google announced an initiative called Project Owl to provide algorithmic updates to surface more authoritative content" and stamp out fake news stories from its search results. To some, that was an uncomfortable step toward Google becoming an arbiter of what is and is not a trustworthy news source. "They're really skating on thin ice," said Michael Bertini, a search strategist at iQuanti, a digital marketing agency. "They're controlling what users see." In an open letter to Google last month, Mr. North traced his site's traffic decline to Project Owl. Mr. North said he believed that Google was blacklisting the site, using concerns over fake news as a cover to suppress opinions from socialist, antiwar or left-wing websites and block news that Google doesn't want covered.