As President Donald Trump and Twitter sparred this week, Silicon Valley has waded into an increasingly partisan debate over free expression.

The deepening feud between the president and his go-to social media platform is forcing companies like Facebook and Google to gird for a lobbying battle to defend the legal protections that underpin their lucrative business models, sooner and much more publicly than they had originally expected.

As Trump and Twitter sparred this week, NetChoice — whose members include Facebook, Twitter, Google and scores of other big-name online companies — rushed into an effort to convince the American public that Trump is wrong about an obscure provision of a quarter-century-old communications law.

The Internet Association, which represents Twitter, Google and Facebook, among others, speedily released a video arguing that the internet depends on the liability protections at the center of the fight.

Trump, Szabo said, is “using government to attack the free speech rights of internet companies.” (Trump has made the opposite argument, saying Washington must protect free expression from political censorship by liberal Silicon Valley).

The 1996 statute offers online platforms broad immunity from lawsuits over the messages, photos, videos and other content their users post — a protection that has helped companies like Facebook and Google amass some of the world's biggest corporate fortunes.

The rest of Silicon Valley was more than happy to let Facebook bear the brunt of criticisms over data privacy and Google endure the hottest antitrust spotlight.

Twitter, meanwhile, escalated its crackdown on Trump early Friday, labeling a Trump tweet containing the phrase “when the looting starts, the shooting starts” in response to protests in Minneapolis as “glorifying violence.” The White House then tweeted Trump's words verbatim, prompting Twitter to append the same warning label onto the official White House account

In another test for Twitter's policies, Trump tweeted Saturday morning that the protesters who had massed outside the White House the previous night would "have been greeted with the most vicious dogs, and most ominous weapons, I have ever seen" had they breached the grounds

While Twitter has its own policy priorities in Washington, Section 230 and other content regulations chief among them, it has fewer entanglements in the nation’s capital than its Silicon Valley counterparts

It has recently been more willing to antagonize the Trump administration than some other tech companies, and has previously said that its generally hands-off approach to world leaders doesn’t mean Trump’s tweets can’t be pulled from the platform

“Twitter is acting now because they can,” said Nu Wexler, a former spokesperson for Google, Facebook and Twitter

It’s no real surprise that Trump would go after Silicon Valley as he did

In mid-May, the president tweeted that the "Radical Left is in total command & control of Facebook, Instagram, Twitter and Google," urging his 80 million followers to "stay tuned."