Remember when Donald Trump hinted that he would threaten to restructure the US debt to get better terms on it? His protectionist measures may “help” him to achieve some sort of restructuring, but not in a good way.

President Trump’s protectionist tariffs on steel and aluminium are very likely just the beginning of a long protectionist streak in the US. And while his country’s own economy will suffer because of retaliatory measures elsewhere, other countries are likely to take bigger hits.

When a big economy imposes tariffs, some of the countries that export to it may choose to lower prices in order to protect some of their market share. This benefits the big economy, because it is essentially a transfer of wealth from the exporter to the importer.

The fear that US protectionism will hurt the eurozone was clear in a sentiment survey by the Frankfurt-based sentix Institute published last week.

Following the US president’s announcements of tariffs on steel and aluminium, US economic policy is judged much more negatively by investors surveyed by the institute. The component index for US trade policy of its sentiment index fell sharply to -0.91 points from -0.51.

It will not be long before President Trump turns his fury against Germany, which has the world’s largest trade deficit, as Albert Edwards, the renowned bearish Societe Generale economist, pointed out in research published last week.

“The US has not been alone in criticising Germany’s outsized external surplus; so too have the European Commission, the IMF and the OECD,” he wrote. “Germany’s surplus is now, in dollar terms, the biggest in the world. The eurozone surplus has also been rising in recent years to stand at 4% of GDP.”

One reason for this is the exchange rate. Germany benefits from the fact that it is lumped together with weaker economies in the eurozone, and the euro is not as strong as a German-only currency would be.

So if President Trump thinks this is a plot by Germany to take advantage of the US economy, he should look more carefully at the role played by exchange rates and debt.

The mirror image of the trade deficit or surplus is of course the capital surplus, or deficit. The US has a capital surplus with the world because foreigners buy its debt in order to finance its imports. If the US imports less, these foreigners will have less need to buy the US debt.

Less demand for US debt would push down US Treasury bond prices and raise their yields, which move inversely to prices. This would raise interest rates for all US borrowers. A restructuring of debt of sorts, just probably not the kind President Trump was talking about.