Along the thin strip of beach and woodland known as the Vistula Spit which marks the northernmost demarcation between Poland and the Russian exclave of Kaliningrad, there is not much in the way of a border.

Just some torn wire fencing and a few rotten posts which seem to stagger drunkenly into the shallows of the Baltic Sea.

Beneath a sign barring entry, we find a couple of empty bottles of Russian cognac and vodka.

It doesn’t feel like the edge of NATO territory.

“I don’t see much protection. It’s not good,” says Krzysztof from Katowice, who has come to inspect the border himself.

“We have to have some kind of scare tactic, something to show that we are trying to strengthen our army,” says Grzegorz, who lives nearby.

“At the same time I think I would not base the defence of our country solely on our army. I am convinced that Europe or America, if anything were to happen, will help us 100%.”

Poland is investing massively in its defence, with military spending set to hit 4.7% of GDP in 2025, more than any other NATO country.

Polish Prime Minister Donald Tusk has said he will introduce voluntary military training for men of any age, and women too should they wish, so the army has a competent reserve force in the event of war.

He is investing $2.5bn in stronger border fortifications between Russia and Belarus, a project called East Shield which will include anti-tank obstacles, bunkers and potentially minefields too.

Along with its Baltic neighbours, Poland is withdrawing from the Ottawa convention against the use of land mines. It hasn’t committed to using them, but it wants to have that option.

We’ve been granted access to one of the cornerstones of Polish, and European defence, which is a couple of hours drive from the Vistula spit at the Redowicze military base.

Aegis Ashore Poland, together with its sister site in Romania, are the land-based arms of NATO’s missile defence shield over Europe, which is run by the US navy.

They are symbols of the US commitment to NATO and to the protection of Europe.

And despite changes at the top of the Pentagon it is “business as usual”, says Captain Michael Dwan who oversees air and missile defence within the US Sixth Fleet.

“Our mission to work with NATO forces has been unchanged. And so our commitment from the United States perspective and what capability we bring to ballistic missile defence and the defence of NATO is championed here in Poland.”

As far as Russia is concerned, NATO’s two missile defence bases in Romania and Poland represent a NATO threat on their doorstep and are therefore a “priority target for potential neutralisation”, per Russia’s foreign ministry.

NATO says the installations are purely defensive and their SM-3 interceptor missiles are not armed and are not intended to carry warheads. Russia counters they could easily be adapted to threaten Russia.

Not the case, Captain Dwan says.

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“It’s not a matter of moving offensive weapons here into the facility, the hardware and the infrastructure is simply not installed.

“It would take months or years to change the mission of this site and a significant amount of money and capability and design.”

With so much marked “secret” on the site, it seems amazing to be granted the access.

But for NATO, transparency is part of deterrence. They want potential adversaries to know how sophisticated their radar and interception systems are.

They know that if they carried warheads on site, that would make them a target so they don’t.

Deterrence also depends on whether potential adversaries believe in the US’s commitment to NATO and to Europe’s defence.

On an operational level, as far as the troops are concerned, that commitment may still be iron-clad.

But as far as its commander-in-chief goes, there is still – as with so much around Donald Trump’s presidency – a great deal of uncertainty.

In the Oval Office on Wednesday afternoon President Trump suggested he might bundle a potential US troop drawdown in Europe together with the issue of EU trade and tariffs.

“Nice to wrap it up in one package,” he said, “it’s nice and clean”.

Probably not the way Europe sees it, not with a resurgent Russia on their doorstep, economic tailwinds breeding animosity and the notion of Pax Americana crumbling at their feet.

The market rollercoaster of the past week – the tariffs, the jeopardy, the brinkmanship – has highlighted the remarkable nature of an interconnected world we take for granted.

There are many frontlines in this global trade war and the port of Duluth-Superior is one. It is a logistical and an engineering wonder.

In the northernmost part of the United States, near the border with Canada, there is no seaport anywhere in the world as far inland as this.

The sea is more than 2,000 miles away, to the east, along the Great Lakes-St Lawrence Seaway System, a binational waterway with a shared border between the US and Canada.

On the portside, vast ocean-going vessels are loaded and unloaded with products which make up the lifeblood of the global economy – iron ore for Canada, cement from Turkey, grain for Algeria and shipping containers packed with “Made in China” products for the American market.

My guide is Jayson Hron from the Duluth Seaway Port Authority.

“A vessel that is sailing through the seaway to Duluth crosses the international boundary nearly 30 times on that journey,” he tells me.

Duluth-Superior generates $1.6bn (£1.2bn) a year, supports more than 7,000 jobs, and these are nervous times.

“It’s certainly a season of more unpredictability than we’ve seen in the last few years. Unpredictability is bad for ports and bad for supply chains,” Mr Hron says.

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Tariffs mean friction and friction is bad for everyone. Approximately 30 million metric tons of waterborne cargo moves through the port each season, placing it among the nation’s top 20 ports in terms of cargo flow.

“Iron ore is the port’s king cargo by tonnage,” Mr Hron says. “It makes up about half of our waterborne tonnage total each year. It is mined 65 miles/104km from the port, on Minnesota’s Iron Range.”

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But not all of the iron ore sails to domestic mills. Almost a third sailed to Canada in 2024, now subject to the trade war levies between the two nations.

“A fifth of our port’s overall waterborne tonnage was Canadian trade in 2024, with the vast majority of it export tonnage from the US to Canada,” Mr Hron says.

Geography combined with American and Canadian engineering over many decades has made this port a logistical wonder. From the high seas, cargo can be imported and exported to and from the heart of the North American continent.

On the dockside, the Federal Yoshino is being prepared for her cargo. She will leave here soon with American grain destined for Algeria.

The port straddles two states. The John A Blatnik interstate bridge links Duluth with Superior and Minnesota with Wisconsin.

A network of roads and rails links the port with the country beyond, and an hour to the southeast are the fields of gold in Wisconsin.

Trump suggests farmers can sell more products at home

Last year, soybeans were the biggest export from the US to China, totalling nearly $12.8bn (£10bn) in trade.

Donald Trump has suggested American farmers can make up the difference by selling more of their products at home.

In March, he posted on social media: “To the Great Farmers of the United States: Get ready to start making a lot of agricultural product to be sold INSIDE of the United States. Tariffs will go on external product on April 2nd. Have fun!”

But there is no solid domestic market for soybeans – America’s second largest crop. Two-fifths of the exports go to China. No other export market comes close – 11% to Mexico and 9% to the EU – also now facing potential tariff barriers too.

‘These fields are rows of gold’

Tanner Johnson is a local farmer and soybean industry representative. He talks regularly to politicians in Washington DC.

“They don’t look like much in your hand. But these fields are rows of gold,” he says.

Farmers across this country voted overwhelmingly for Mr Trump. Is there anxiety? Absolutely.

“I don’t want to put an exact timeline on when doors around here will close. But in the short term I think most farmers can handle it. Long-term – a year, year plus – things are going to look a lot more bleak around here,” Mr Johnson tells me.

Here, they mostly seem to hold on to a trust in Mr Trump. There remains a belief that his wild negotiating with their livelihoods will pay off. But it’s high stakes and with an uncertainty that no one needs.

Chalk this one up to the bond vigilantes.

This is the term used periodically to describe investors who push back against what are perceived to be irresponsible fiscal or monetary policies by selling government bonds, in the process pushing up yields, or implied borrowing costs.

Most of the focus on markets in the wake of Donald Trump’s imposition of tariffs on the rest of the world has, in the last week, been about the calamitous stock market reaction.

This was previously something that was assumed to have been taken seriously by Mr Trump.

During his first term in the White House, the president took the strength of US equities – in particular the S&P 500 – as being a barometer of the success, or otherwise, of his administration.

He had, over the last week, brushed off the sour equity market reaction to his tariffs as being akin to “medicine” that had to be taken to rectify what he perceived as harmful trade imbalances around the world.

But, as ever, it is the bond markets that have forced Mr Trump to blink – and, make no mistake, blink is what he has done.

To begin with, following the imposition of his tariffs – which were justified by some cockamamie mathematics and a spurious equation complete with Greek characters – bond prices rose as equities sold off.

That was not unusual: big sell-offs in equities, such as those seen in 1987 and in 2008, tend to be accompanied by rallies in bonds.

However, this week has seen something altogether different, with equities continuing to crater and US government bonds following suit.

At the beginning of the week yields on 10-year US Treasury bonds, traditionally seen as the safest of safe haven investments, were at 4.00%.

By early yesterday, they had risen to 4.51%, a huge jump by the standards of most investors. This is important.

The 10-year yield helps determine the interest rate on a whole clutch of financial products important to ordinary Americans, including mortgages, car loans and credit card borrowing.

By pushing up the yield on such a security, the bond investors were doing their stuff. It is not over-egging things to say that this was something akin to what Liz Truss and Kwasi Kwarteng experienced when the latter unveiled his mini-budget in October 2022.

And, as with the aftermath to that event, the violent reaction in bonds was caused by forced selling.

Now part of the selling appears to have been down to investors concluding, probably rightly, that Mr Trump’s tariffs would inject a big dose of inflation into the US economy – and inflation is the enemy of all bond investors.

Part of it appears to be due to the fact the US Treasury had on Tuesday suffered the weakest demand in nearly 18 months for $58bn worth of three-year bonds that it was trying to sell.

But in this particular case, the selling appears to have been primarily due to investors, chiefly hedge funds, unwinding what are known as ‘basis trades’ – in simple terms a strategy used to profit from the difference between a bond priced at, say, $100 and a futures contract for that same bond priced at, say, $105.

In ordinary circumstances, a hedge fund might buy the bond at $100 and sell the futures contract at $105 and make a profit when the two prices converge, in what is normally a relatively risk-free trade.

So risk-free, in fact, that hedge funds will ‘leverage’ – or borrow heavily – themselves to maximise potential returns.

The sudden and violent fall in US Treasuries this week reflected the fact that hedge funds were having to close those trades by selling Treasuries.

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Confronted by a potential hike in borrowing costs for millions of American homeowners, consumers and businesses, the White House has decided to rein back its tariffs, rightly so.

It was immediately rewarded by a spectacular rally in equity markets – the Nasdaq enjoyed its second-best-ever day, and its best since 2001, while the S&P 500 enjoyed its third-best session since World War Two – and by a rally in US Treasuries.

The influential Wall Street investment bank Goldman Sachs immediately trimmed its forecast of the probability of a US recession this year from 65% to 45%.

Of course, Mr Trump will not admit he has blinked, claiming last night some investors had got “a little bit yippy, a little bit afraid”.

And it is perfectly possible that markets face more volatile days ahead: the spectre of Mr Trump’s tariffs being reinstated 90 days from now still looms and a full-blown trade war between the US and China is now raging.

But Mr Trump has blinked. The bond vigilantes have brought him to heel. This president, who by his aggressive use of emergency executive powers had appeared to be more powerful than any of his predecessors, will never seem quite so powerful again.