With the imposition of a state of siege in Boston, a historical threshold has been crossed. For the first time ever, a major American city has been placed under the equivalent of martial law. The already frayed veneer of a stable democracy based on constitutional principles is in shreds.

On Monday, April 15, two bombs exploded near the finish line of the Boston Marathon in the city’s center. Three people were killed and over 170 were injured, some seriously. This was a criminal act with tragic consequences. But violence, including acts of mass homicide and disasters resulting in major loss of life, is a regular feature of American society. Even as the events in Boston were unfolding, a factory explosion in Texas, to all appearances linked to safety hazards, took far more lives than the bombs detonated at the end of the marathon.

There is no precedent for the massive mobilization of military, police and intelligence forces carried out April 19 in Boston and its environs, which encompass more than 1 million people. Thousands of heavily armed police and National Guard troops occupied the streets, backed up by machine gun-mounted armored vehicles, Humvees and Black Hawk helicopters. As the WSWS noted, the scene resembled the US occupation of Baghdad.

The people were told to remain indoors while police, with automatic weapons drawn, conducted warrantless house-to-house searches. Some of those who strayed out of doors were surrounded by police and ordered to go home. The mass transit system was shut down; passenger train service along the northeastern corridor was halted; businesses, universities and other public facilities were closed.

Boston—the cradle of the American Revolution, one of the most liberal cities in one of the most liberal states in the US, the country’s premier center of higher education—was turned into an armed camp. This staggering mobilization of federal, state and local police power was deployed to track down a 19-year-old youth.

So far, there has been no protest from within the political or media establishment to the lockdown.

Following the capture of alleged bomber Dzhokhar Tsarnaev, President Obama issued a late-night statement from the White House in which he stressed the role of his administration in the police-state mobilization, boasting that he had “directed the full resources of the federal government…to increase security as needed.” Ignoring the presumption of innocence, he referred to the captured suspect and his dead brother as “these terrorists.”

Obama’s Justice Department quickly announced that it would not read the suspect his “Miranda right” to remain silent and obtain legal counsel before speaking to police investigators. It would instead question the seriously injured youth “extensively” not just on matters related directly to public safety, but more broadly on “intelligence matters.” This sets a precedent for denying these rights to anyone arrested under antiterrorism statutes, which, under Obama, has already included political dissidents such as Occupy Wall Street and anti-NATO protesters.

Encouraged by the police-military mobilization, Republican senators Lindsey Graham and John McCain and New York Congressman Peter King, all of whom have close ties to the military and intelligence agencies, demanded that Tsarnaev be declared an enemy combatant and turned over to the military.

The events in Boston have laid bare the modus operandi for the establishment of dictatorial forms of rule in the US. One or another violent act carried out by disoriented or disaffected individuals, perhaps with the help of elements within the state, is declared a terrorist event. A state of siege is imposed suspending democratic rights and establishing military-police control.

So deeply implicated are all of the organs of the state in these plans that little in the outer trappings of political life would have to be changed. It would not be necessary to overthrow the president or shut down Congress. These institutions would readily play their assigned role, and the imposition of a military dictatorship would be sanctioned by the US Supreme Court.

The media would simply continue to do what it normally does—functioning as a de facto arm of the state and providing the necessary pretexts, while whipping up the requisite fear and panic within the public.

The very fact that the entire establishment agrees that democratic norms cannot be maintained in the face of violence by a handful of people testifies to the advanced stage of the breakdown of American democracy.

So disproportionate was the scale of the response to the actual level of the threat that the conclusion cannot be avoided that the Boston bombings were the pretext for, not the cause of, the lockdown. The police-state mobilization was the culmination of more than a decade of intensive planning and the ceaseless buildup of the repressive forces of the state since 9/11, carried out under the cover of the “war on terror.”

The operation is not an expression of strength or confidence on the part of the American ruling class. On the contrary, it reflects the near panic of the corporate-financial elite in the face of mounting social discontent, exacerbated by extreme nervousness over the precarious state of global financial markets. What haunts the ruling class is not the fear of a terrorist attack, but dread of a new financial collapse, with the likely consequence of massive social upheavals.

The breakdown of American democracy has profound causes, the first of which is the staggering level of social inequality. Democracy cannot be maintained when the richest 5 percent of the population controls over 60 percent of the wealth. In the moves to police-military dictatorship, the forms of rule are coming into conformance with the underlying social reality of American capitalism.

Another fundamental cause of the crisis of democracy is the eruption of US militarism. The power of the military/intelligence apparatus has grown immensely, particularly since the end of the Soviet Union, as the American ruling class has turned to military aggression as a means of offsetting the decline in its global economic position. The professional military, segregated from society at large and hostile to it, has acquired ever-greater influence over political affairs and civilian authority. As always, imperialist war is incompatible with democracy.

American liberalism as a distinct political tendency has ceased to exist. The lining up of the Democratic Party behind the “war on terror,” and the external aggression and internal repression carried out in its name, has made clear that there is no section of the ruling elite that will defend democratic rights. The Obama administration, which has expanded the right-wing, antidemocratic policies of the Bush administration, is without question the most reactionary in US history.

As always, the filthiest role is played by the media and its leading personnel. From day one, they turned the airwaves into a continual rumor mill, making one unsubstantiated claim after another in an effort to sow fear and panic and justify the police-state measures being taken. They readily agreed to self-censor their reports in accordance with the demands of the police agencies. As CNN anchor Chris Cuomo, son of the former Democratic governor of New York and brother of the state’s current governor, told viewers, “We’ve only been showing the feeds that authorities are comfortable with.”

The media seeks to create an aura of popular support for martial law-type measures. But the initial confusion will give way to mounting disquiet. The abrupt shift in the forms of rule will create opposition in the population, above all in the working class.

The appropriate conclusions need to be drawn. Social inequality and war—the inevitable outcome of capitalism—are incompatible with democracy. One or the other—capitalism or democracy—must go. That is the issue confronting the working class.