On the campaign trail, Donald Trump pledged to use tariffs to revitalise American industry, bringing jobs home and helping to make America great again. But more than six months into his administration, experts say the president’s trade war is increasingly being wielded as a political cudgel, in lieu of more traditional forms of diplomacy.

The president’s current target, India, has been unable to reach a trade agreement and Trump appears ready to follow through with his threat to impose a further 25% tariff on Delhi – bringing the total to 50% – the joint highest levy on any country, along with Brazil.

It is a whiplash-inducing turnaround from a few months ago, when the newly minted Trump administration seemed intent on continuing a years-long bipartisan effort to deepen ties with India as a geopolitical counterweight to China. It’s part of a trend which highlights how tariffs are used as threats against countries perceived to be recalcitrant. Rather than a tool of economic coercion, Trump instead wields tariffs as a political weapon.

Five rounds of trade talks between the two sides have brought India no closer to conceding to US demands that it open up its vast agriculture and dairy sectors. Negotiations planned for early next week have been abruptly called off, as India’s prime minister, Narendra Modi, grapples with Trump’s demand that India cease to buy oil from Russia; sales that the US says are helping to fuel Vladimir Putin’s war against Ukraine.

The demand – that India wean itself off the Russian oil, which accounts for about 35% of its total supply – sits at odds with the original stated purpose of Trump’s tariff regime: to bring manufacturing back to the US and rebalance trade deficits.

“Tariffs have a very specific purpose of protecting domestic industry from competition,” says Dr Stuart Rollo from the Centre for International Security Studies at the University of Sydney. “That’s not really what this is about … It’s kind of pivoted to a tool of geopolitical compulsion.”

Trump himself has come to admit this. Along with the threatened additional 25% tariff on India in retaliation for continuing to purchase Russian oil, the president has tied Canada’s 35% tariff to its recognition of Palestinian statehood.

In the case of Brazil – which has a rare trade surplus with the US, meaning it buys more than it sells – Trump has stated that the huge 50% tariff is due to the trial of his political ally, Jair Bolsonaro, who is charged with plotting a military coup after he lost the 2022 presidential election.

The president’s top trade adviser, Peter Navarro, even has a new term for these explicitly political trade threats: “national security tariffs”.

The Democratic senator Chris Murphy put it more bluntly, writing in the Financial Times in April that the tariffs are not designed as economic policy but as a “means to compel loyalty to the president”.

Rollo says: “It’s a way of the United States to compel as much of the world as possible into realignment with its global leadership at a time when its actual weight and gravity is diminishing.”

In some ways, this is not new; the Biden administration used trade restrictions to limit China’s access to state of the art semiconductors at a time of heated geopolitical tensions.

But Devashish Mitra, professor of economics at Syracuse university, says that for many in India, the threat faced over Russian oil purchases seems incoherent, ill thought out, and could push India closer to China.

“India did consider the US an ally,” says Mitra. “It was a country that the US was relying on as a counter to China in that region. So it had a huge geopolitical importance, but it doesn’t seem like Trump values any of that.”

This week China’s foreign minister has been in Delhi for talks, and Modi is expected in Shanghai at the end of the month; his first visit in seven years. It’s a part of a recent pattern of tightening relations between the Brics countries – Brazil, Russia, India, China and South Africa, which make up 40% of global GDP – that experts say is a response to Trump’s aggressive trade policies.

For future US administrations, winning back the trust of some of these countries could be difficult, as Trump’s escalating trade war comes at the same time as his administration dismantles its instruments of global statecraft. From mass firings at the state department, to the slashing of foreign assistance programmes at USAID, America’s diplomatic toolbox is vastly diminished.

Tariffs have “come to replace diplomacy”, says Rollo.

And so with his attention divided between crises at home and abroad, the president has left himself armed with only a hammer, with every global flashpoint looking to him like a nail.