Is this the new war? After hot war and cold war comes trade war, Trump-style. The latest battle seems to merely pit scotch against bourbon and camembert against Google, but the US’s argument with the outside world is escalating, and it is no joke.

Donald Trump came to power with a somewhat admirable aversion to overseas military intervention (while maintaining willingness to drop bombs on foreign soil). He saw no gain in his soldiers dying in other people’s wars. To him, foreign policy was transactional. You scratch my back, I scratch yours – and to hell with globalisation and new world orders. He said before his election that The US was “the big, stupid bully and we were systematically ripped off by everybody”, and expressed his desire for tariffs.

The US has also turned its back on collective discipline or arbitration. Trump sees trade as a knife fight

The steady drip of US disengagement from global cooperation has become a torrent. Trump has put sanctions in place against Iran, Russia, Venezuela, Argentina, Zimbabwe, Syria and other sovereign states. To this add retaliatory tariffs and quotas on everything from Brazilian steel to European cars, with the list lengthening every month.

The US has also turned its back on collective discipline or arbitration. Trump sees trade as a knife fight. His trade adviser, Peter Navarro, believes economic security is indivisible from national security. He has threatened to block the budget of the World Trade Organization, pulled out of the Trans-Pacific Partnership for trade, reneged on the Paris climate deal and the Iran nuclear deal, and withdrew from international court of justice protocols outlining diplomatic relations, as well as leaving Unesco.

As in most wars, there is always a grievance just sufficient to escalate the confrontation. There is no doubt that China was taking advantage of the US in trade. The EU was aiding Airbus against Boeing. On the other hand, America’s digital giants were avoiding Europe’s taxes while savaging its retailers. Boris Johnson’s decision to join France in a levy of between 2% and 3% on them mocks any post-Brexit sweetheart deal with Washington: let’s see what “take back control” means when Trump orders Johnson to scrap his digital tax.

Optimists sigh that one day Trump will be gone, and a surge of collective discipline will return to the world economy. I doubt it. The global economic consensus died in 2008 with the financial crisis. The forces of commercial chauvinism on which Trump, Johnson and other populists rely are deep-seated. Besides, this is a conflict in which more sinister weapons than tariffs and sanctions are ready to be deployed. They are typified by the backdrop to the row over China’s Huawei, with trade entangled in cybersecurity, espionage and national security.

As described in Andy Greenberg’s analysis of cyberwar, Sandworm, official and unofficial hacking has reversed the strategic advantage that defence in war has long held against attack. A kid with a laptop can access virtually the entire electronic infrastructure of a modern state. If war’s purpose is to devastate territory and put governments and people under duress, it can now be waged from an office in Moscow, Washington, Tehran or anywhere else. Power grids, waste-water plants and cash servers can be crashed and frozen. Life support, in every sense of the term, can be ended. These weapons are not digital fantasies: the US (or Israel) appears to have regularly penetrated Iran’s nuclear facilities. In return, Iran briefly sabotaged New York’s water supply and the cash servers of American Express and Wells Fargo.

Such weapons clearly go way beyond commercial sanctions, though you may end up just as dead from a banned medical supply as from a missile or drone. And the alarming difference is that this economic belligerence, by seeming outwardly less bloodthirsty, is all the more tempting to those eager to wield power. Last summer Trump decided not to bomb Iran for downing an American drone because it was not a proportionate response – but the savagery of his sanctions and cyberwar against Iran did not abate. Indeed the widely held view that sanctions may hurt but are seldom politically effective merely invites escalation. Trump’s treasury secretary, Steven Mnuchin, claims to spend half his time on sanctions. Why does the US need to bother with the Pentagon when it has a treasury on the attack?

This must transform the concept of defence. For the US, Russia, China and, absurdly, Britain, to send armies and ships roaming the globe looking for someone to fight seems ever more senseless. Perhaps the left was right after all: power has been inverted and weak become strong. The defence that ever more complex and therefore vulnerable economies need is against any regime with a grievance, against anarchism and techno-terrorism. Rather than globalise, countries such as the US and China will become introverted, isolating themselves and their economies. They will erect digital walls round their social and commercial infrastructure, and too bad if everyone else suffers. For them, free trade means Trojan horse.

These new forms of conflict have yet to find their Clausewitz. In the 19th century the military theorist rationalised war’s “primordial violence, hatred and enmity” by seeing it as a “continuation of political intercourse by other means”. Those other means have changed: their weapons are digital and commercial. But this has merely given licence to the Trumps now strutting the electronic and diplomatic battlefields, jeering at anyone seeking concord between nations. The sanction, the tariff and the hacker point to uncharted territory – but that is certainly where we are going.

• Simon Jenkins is a Guardian columnist