You need not be a media historian to notice that we live in a golden age of press harassment, domestic propaganda and coercive efforts to control political debate. The Trump White House repeatedly seeks to discredit the press, threatens to strip broadcasters of their licenses and calls for the firing of journalists and football players for speaking their minds. A foreign government tries to hack our elections, and journalists and public speakers are regularly attacked by vicious, online troll armies whose aim is to silence opponents.

In this age of “new” censorship and blunt manipulation of political speech, where is the First Amendment? Americans like to think of it as the great protector of the press and of public debate. Yet it seems to have become a bit player, confined to a narrow and often irrelevant role. It is time to ask: Is the First Amendment obsolete? If so, what can be done?

These questions arise because the jurisprudence of the First Amendment was written for a different set of problems in a very different world. The First Amendment was ignored for much of American history, coming to life only in the 1920s thanks to the courage of judges like Learned Hand, Louis Brandeis and Oliver Wendell Holmes. Courts and civil libertarians used the amendment to protect speakers from government prosecution and censorship as it was practiced in the 20th century, such as the arrest of pamphleteers and the seizure of anarchist newspapers by the Postal Service.

But in the 21st century, censorship works differently, as the writer and academic Zeynep Tufekci has illustrated. The complete suppression of dissenting speech isn’t feasible in our “cheap speech” era. Instead, the world’s most sophisticated censors, including Russia and China, have spent a decade pioneering tools and techniques that are better suited to the internet age. Unfortunately, those new censorship tools have become unwelcome imports in the United States, with catastrophic results for our democracy.

The Russian government was among the first to recognize that speech itself could be used as a tool of suppression and control. The agents of its “web brigade,” often called the “troll army,” disseminate pro-government news, generate false stories and coordinate swarm attacks on critics of the government. The Chinese government has perfected “reverse censorship,” whereby disfavored speech is drowned out by “floods” of distraction or pro-government sentiment. As the journalist Peter Pomerantsev writes, these techniques employ information “in weaponized terms, as a tool to confuse, blackmail, demoralize, subvert and paralyze.”

Our distressing state of public discourse stems from the widespread use of these new tools of censorship and speech control, including by the White House. The administration habitually crosses the line between fact and propaganda. Instead of taking action itself, it demands that others punish its supposed enemies. To add to the mess, it is apparent that the Russian government and possibly others hope to manipulate American political debate, as its exploitation of Facebook and Twitter in the last election shows.

What can be done? It is time to recognize that the American political process and marketplace for ideas are under attack, and that reinvigorating the First Amendment is vital. First, it is an imperative that law enforcement and lawmakers do more to protect journalists and other public speakers from harassment and threats. Cyberstalking is a crime. And as the Supreme Court has made clear, threats of violence are not protected speech. A country where speaking one’s mind always results in death threats is not a country that can be said to be truly free.

Second, too little is being done to protect American politics from foreign attack. The Russian efforts to use Facebook, YouTube and other social media to influence American politics should compel Congress to act. Social media has as much impact as broadcasting on elections, yet unlike broadcasting it is unregulated and has proved easy to manipulate. At a minimum, new rules should bar social media companies from accepting money for political advertising by foreign governments or their agents. And more aggressive anti-bot laws are needed to fight impersonation of humans for propaganda purposes.

Finally, the White House needs to be held accountable when it tries to use private parties to circumvent First Amendment protections. When it encourages others to punish its critics — as when it demanded that the N.F.L., on pain of tax penalties, censor players — it is wielding state power to punish disfavored speech. There is precedent for such abuses to be challenged in court.

Some might argue, based on the sophomoric premise that “more speech is always better,” that the current state of chaos is what the First Amendment intended. But no defensible free-speech tradition accepts harassment and threats as speech, treats foreign propaganda campaigns as legitimate debate or thinks that social-media bots ought to enjoy constitutional protection. A robust and unfiltered debate is one thing; corruption of debate itself is another. We have entered a far more dangerous place for the republic; its defense requires stronger protections for what we once called the public sphere.