This week’s deployment of Blackhawk helicopters in Chicago is only the latest in a series of “urban warfare training” exercises that have become a familiar feature of American life.

As elsewhere, this exercise was sprung unannounced on a startled civilian population. Conducted in secrecy, apparently with the collusion of local police agencies and elected officials, Democrats and Republicans alike, the ostensible purpose of these exercises is to give US troops experience in what Pentagon doctrine refers to as “Military Operations on Urban Terrain.”

Such operations are unquestionably of central importance to the US military. Over the past decade, its primary mission, as evidenced in Afghanistan and Iraq, has been the invasion and occupation of relatively powerless countries and the subjugation of their resisting populations, often in house-to-house fighting in urban centers.

The Army operates a 1,000 acre Urban Training Center in south-central Indiana that boasts over 1,500 “training structures” designed to simulate houses, schools, hospitals and factories. The center’s web site states that it “can be tailored to replicate both foreign and domestic scenarios.”

What does flying Blackhawks low over Chicago apartment buildings or rolling armored military convoys through the streets of St. Louis accomplish that cannot be achieved through the sprawling training center’s simulations? Last year alone, there were at least seven such exercises, including in Los Angeles, Chicago, Miami, Tampa, St. Louis, Minneapolis and Creeds, Virginia.

The most obvious answer is that these exercises accustom troops to operating in US cities, while desensitizing the American people to the domestic deployment of US military might.

Preparations for such deployments are already far advanced. Over the past decade, under the pretext of prosecuting a “global war on terror,” Washington has enacted a raft of repressive legislation and created a vast new bureaucracy of state control under the Department of Homeland Security. Under the Obama administration, the White House has claimed the power to throw enemies of the state into indefinite military detention or even assassinate them on US soil by means of drone strikes, while radically expanding electronic spying on the American population.

Part of this process has been the ceaseless growth of the power of the US military and its increasing intervention into domestic affairs. In 2002, the creation of the US Northern Command for the first time dedicated a military command to operations within the US itself.

Just last May, the Pentagon announced the implementation of new rules of engagement for US military forces operating on American soil to provide “support” to “civilian law enforcement authorities, including responses to civil disturbances.”

The document declares sweeping and unprecedented military powers under a section entitled “Emergency Authority.” It asserts the authority of a “federal military commander” in “extraordinary emergency circumstances where prior authorization by the president is impossible and duly constituted local authorities are unable to control the situation, to engage temporarily in activities that are necessary to quell large-scale, unexpected civil disturbances.” In other words, the Pentagon brass claims the unilateral authority to impose martial law.

These powers are not being asserted for the purpose of defending the US population against terrorism or to counter some hypothetical emergency. The US military command is quite conscious of where the danger lies.

In a recent article, a senior instructor at the Fort Leavenworth Command and General Staff College and former director of the Army’s School of Advanced Military Studies laid out a telling scenario for a situation in which the military could intervene.

“The Great Recession of the early twenty-first century lasts far longer than anyone anticipated. After a change in control of the White House and Congress in 2012, the governing party cuts off all funding that had been dedicated to boosting the economy or toward relief. The United States economy has flatlined, much like Japan’s in the 1990s, for the better part of a decade. By 2016, the economy shows signs of reawakening, but the middle and lower-middle classes have yet to experience much in the way of job growth or pay raises. Unemployment continues to hover perilously close to double digits …”

In other words, the Pentagon sees these conditions—which differ little from what exists in the US today—producing social upheavals that can be quelled only by means of military force.

What is being upended, behind the scenes and with virtually no media coverage, much less public debate, are constitutional principles dating back centuries that bar the use of the military in civilian law enforcement. In the Declaration of Independence itself, the indictment justifying revolution against King George included the charge that he had “affected to render the Military independent of and superior to the Civil power.”

Side by side with the rising domestic power of the military, the supposedly civilian police have been militarized. An article published by the Wall Street Journal last weekend entitled “The Rise of the Warrior Cop” graphically described this process:

“Driven by martial rhetoric and the availability of military-style equipment—from bayonets and M-16 rifles to armored personnel carriers—American police forces have often adopted a mind-set previously reserved for the battlefield. The war on drugs and, more recently, post-9/11 antiterrorism efforts have created a new figure on the US scene: the warrior cop—armed to the teeth, ready to deal harshly with targeted wrongdoers, and a growing threat to familiar American liberties.”

The article describes the vast proliferation of SWAT (Special Weapons and Tactics) units to virtually every town in America, fueled by some $35 billion in grants from the Department of Homeland Security, “with much of the money going to purchase military gear such as armored personnel carriers.”

This armed force was on full display in April when what amounted to a state of siege was imposed on the city of Boston, ostensibly to capture one teenage suspect. The entire population of a major American city was locked in their homes as combat-equipped police, virtually indistinguishable from troops, occupied the streets and conducted warrantless house-to-house searches.

Underlying this unprecedented militarization of US society are two parallel processes. The immense widening of the social chasm separating the billionaires and multi-millionaires who control economic and political life from American working people, the great majority of the population, is fundamentally incompatible with democracy and requires other forms of rule. At the same time, the turn to militarism as the principal instrument of US foreign policy has vastly increased the power of the military within the US state apparatus.

Both America’s ruling oligarchy and the Pentagon command recognize that profound social polarization and deepening economic crisis must give rise to social upheavals. They are preparing accordingly.

The working class must draw the appropriate conclusions and make its own political preparations for the inevitable confrontations to come.