Washington, May 29 : US President Donald Trump has signed an executive order that could open the door for federal regulators to punish social media giants Facebook, Google and Twitter for the way they police content online. Trump has portrayed the order as an attempt to stamp out political bias on the part of the country's largest social media platforms, a leading US media outlet reported. His directive comes days after Twitter steered viewers of some of the president's tweets to news articles that fact-checked his claims, a move Trump said was a form of censorship, The Washington Post reported. "We're here today to defend free speech from one of the greatest dangers," Trump said on Thursday before signing the document. But advocates for the tech sector, lawmakers in Congress and a variety of legal experts from across the political spectrum on Thursday doubted the legality of Trump's draft proposal and feared its implications for free speech. Others questioned whether the US government even could carry out the order as the president intended. Some in the tech industry even began quietly discussing their legal options, including a potential lawsuit challenging Trump's order once it is signed, according to two people familiar with the matter who spoke on the condition of anonymity because talks are early. "This is simply setting the wheels of law enforcement and regulation in motion against a private company for questioning the president," said Matt Schruers, president of the Computer and Communications Industry Association, a Washington trade group that represents Facebook, Google and other major tech companies. /IANS