The Won's Immunity Test: Fed Rate Hike Comes With Political Pressure

The Fed Raises Rates. The White House Threatens.

The Federal Reserve is about to do what it hasn’t done in three years: raise its benchmark interest rate. On September 15–16, the FOMC is expected to lift rates by a quarter percentage point to the 3.75–4.00% range, according to CME FedWatch data showing a 92% probability. That number has vaulted from just 33% a month ago and 59% last week, driven by a wave of hotter-than-expected U.S. data — August non-farm payrolls, PPI, and CPI all came in warm.

But what makes this cycle different from every rate-hiking episode since 2022 is the political temperature. President Trump has openly threatened to oppose a Fed rate increase, treating monetary policy as an instrument of political leverage rather than independent economic stewardship. This is not a quiet shift in rhetoric. It is a direct challenge to the institutional credibility that has underpinned the dollar’s reserve status for decades.

Why the Won Is in the Crosshairs

For South Korea, the timing is brutal. The won has been one of the weakest major emerging-market currencies this year, dragged down by the very dollar strength that a Fed hike would intensify. The dollar index sits at 99.8, on the verge of touching the psychological 100 level for the first time since late last year. U.S. 10-year Treasury yields breached 5% on September 14 — the highest since October 2023 — amplifying the pull of American assets away from emerging markets.

Add to this the oil shock: the Middle East conflict is pushing crude above $100 a barrel, and South Korea, one of the world’s largest energy importers, is exquisitely vulnerable. A stronger dollar and higher oil prices together create a pincer movement against the won that no amount of central bank bravado can fully neutralize.

Shin’s Claim of Immunity

This is where Bank of Korea Governor Shin Hyun-song’s recent remarks become both significant and fragile. Speaking at the Jackson Hole symposium in late August, Shin declared that the won had developed “immunity” to external shocks — a phrase chosen carefully, almost defiantly, in a city known for monetary-policy gravitas.

His argument rests on three pillars: two consecutive rate hikes by the BOK (raising the policy rate from 2.50% to 3.00%), a robust current-account surplus, and upwardly revised GDP growth forecasts. Together, he argued, these fundamentals shield the currency from the kind of violent devaluations that have plagued emerging markets in prior Fed tightening cycles.

A senior FX dealer at a major Korean securities firm told Unifirst the market’s view aligns with this logic: if the Fed raises as expected, the dollar-won pair should stop falling and move sideways; if the Fed holds, the won could slip further.

The Single-Hike Problem

Here is what Shin’s optimism glosses over. Since the 1990s, the Federal Reserve has only once ended a rate-hiking cycle after a single increase — in 1997. History suggests the Fed’s September move is not a one-off. It is the opening shot.

Each subsequent hike widens the interest-rate differential between the U.S. and South Korea, eroding the relative appeal of won-denominated assets. The BOK’s proactive stance buys time, but it cannot permanently offset a Fed that is committed to further tightening in a post-Jackson Hole world where inflation data keeps coming in hot.

The structural deficit in Korea’s energy import bill at $100 oil is not a marginal concern. It eats directly into the current-account surplus that Shin cites as the won’s armor. The more oil costs, the thinner that cushion becomes.

The Political Variable No One Is Pricing In

Perhaps the most dangerous variable in this equation is not data-driven at all. Trump’s公开 hostility toward a Fed rate hike introduces a governance risk that markets have no precedent for pricing. If the President pressures the Fed to delay or scale back its tightening cycle — or if the Fed, in an unprecedented breach of independence, accommodates that pressure — the resulting policy confusion could trigger capital flows far more volatile than any FX hedge can manage.

Conversely, if the Fed resists and proceeds with the hike — and with further hikes in prospect — the won faces the full force of a dollar regime that is simultaneously stronger and more politically uncertain. Emerging-market currencies do not distinguish between a hawkish Fed driven by data and a hawkish Fed driven by institutional independence. They flee volatility in both cases.

What Comes Next

The September FOMC meeting is a threshold event. For the won, the immediate question is whether it stabilizes around current levels or breaks lower. But the deeper question — one that extends far beyond Seoul — is whether the Fed’s next moves will be dictated by inflation data alone or will be entangled in a political struggle that reshapes the relationship between central banks and executive power.

Shin Hyun-song’s diagnosis of the won’s immunity is not wrong. It is just incomplete. The foundations he identified — current-account surplus, growth revisions, preemptive rate hikes — matter. But they were built in a world where the Fed’s decisions were expected to follow the data, not the president’s mood. If that world is changing, the won’s immunity may turn out to be conditional.

For investors and policymakers watching from outside Korea, the lesson is broader. A Fed that raises rates under political duress sends a signal that undermines the very credibility that makes the dollar safe. And when dollar credibility wavers, every emerging-market currency — including the won — pays a price that no amount of immunization can fully erase.