Korea vs USA — Debt to GDP

The exception a reserve currency creates

US federal debt stands at 122% of GDP, nearly three times Korea's D1 (45.8%). Yet Treasuries are treated as the safest asset in the world. The more financial markets wobble, the more demand for Treasuries rises and yields actually fall — a pattern observed again and again. That paradox, where the heavily indebted country's bonds sell better in a crisis, sits at the heart of the dollar system.

The reason is that the dollar is the reference currency for global trade settlement and for national foreign exchange reserves. Central banks must park their reserves somewhere, and the Treasury market is effectively the only one deep and liquid enough to absorb them. In other words, the United States receives structural demand for its own debt from outside. Other countries must go find buyers when they borrow more; the US issues into a pool of buyers that already exists.

That difference gives an identical debt ratio a completely different meaning. Transposing 122% onto Korea to argue "the US is at 122%, so Korea has room" rests on the false premise that the two countries raise funds in the same market on the same terms.

Even that privilege has limits

Dollar privilege is not unlimited. As the stock of debt grows, interest costs claim a larger share of the budget. While rates are low, even 122% can be carried at manageable interest; once rates normalise, the interest on the same principal multiplies. That US interest outlays have started to be compared in size with defence or social security spending is the signal of this shift.

About 30% of US Treasuries are also held abroad. Set against Japan's 85% domestic ownership, external dependence is far higher. Foreign holders can trim their positions for political reasons or domestic ones, and that decision feeds straight into US yields. Issuing in your own currency prevents default; it does not prevent rates from rising.

The recurring political standoff over the debt ceiling is a further risk. It creates doubt not about the capacity to pay but about the willingness to pay — something that affects credit assessment regardless of accounting soundness. In short, America's 122% is less evidence that "high is fine" than that "special conditions are still absorbing it."

Why it does not transfer to Korea

Korea is a small open economy and the won's share of international settlement is marginal. When an external shock hits, capital flows out and the currency depreciates; import prices rise and pressure builds to raise rates. Where the United States can cut rates in a crisis, Korea can find itself having to raise them.

So when Korea discusses fiscal space, the benchmark is not the absolute ratio but its link to external soundness. Reserves, the current account and the share of short-term external debt have to be read alongside the fiscal indicators. Even with a low debt ratio, a fragile external position leaves less room for fiscal expansion than the headline suggests.

Conversely, this structure is also why Korea has to hold fiscal discipline more tightly than the United States. A country without the privilege has to build trust as a track record, and a track record is only useful if it exists before the crisis arrives.

What "fiscal space" actually means

Fiscal space does not mean a ceiling up to which a country may borrow. No such threshold exists; it differs across countries and across periods within the same country. In practice, fiscal space is closer to a conditional capacity: can you raise spending when you need to without losing market confidence?

That capacity has three components — the stock of debt and its interest burden, the stability of the currency and exchange rate, and a track record of having kept fiscal discipline. The United States scores badly on the first but overwhelmingly well on the second; Korea scores well on the first but is exposed on the second.

Grasp that composition and it becomes clear why placing the two countries on a single axis is meaningless. What Korea has to manage is not the ratio gap with the United States but staying in a condition where it can actually increase spending when a crisis arrives. That condition is accumulated in calm times.

The order to read this table in

First, confirm that the US figure is federal while Korea's is D1 or D2. US state and local government debt is not in this number. Second, before comparing ratios, compare the international standing of the currencies. When that differs, the ratio comparison loses its meaning.

Third, look at the share of the budget that interest payments absorb. Fourth, read the Korean figure together with reserves and the current account. Fiscal soundness is not a standalone indicator; it holds only in combination with external soundness.