US chip tariffs and the Korea talks, September 4, 2026 — "if you don't build here, expect to pay"

The shape of the US semiconductor tariff came into view in the first week of September. The unusual part is that there is still no rate. What has been disclosed is a condition, not a number.

Commerce Secretary Howard Lutnick said in a September 2 broadcast interview that the administration is preparing a "targeted, thoughtful tariff policy" on semiconductors. He put the core term in one sentence:

If you don't build here, expect to pay to enter the greatest market in the world.

Inverted: companies that do build US production capacity get the tariff waived or reduced.

1. It is a list, not a rate

Under this design the decisive variable is not the percentage but who ends up on the relief side.

TSMC and Micron, both building at scale in the United States, qualify. TSMC has said it is constructing 20 fabs simultaneously worldwide and still cannot keep up with AI demand.

The scope is also under expansion. Alongside chips themselves, the administration has weighed covering finished goods containing chips — data centre servers and laptops — and an August 27 report described eliminating the existing data centre exemption (see "US weighs a second round of semiconductor tariffs, August 27, 2026"). Where that boundary settles determines whether this lands on chipmakers alone, or reaches server and PC builders and then the data centre operators behind them.

2. The empty column at Samsung and SK hynix

It is not that the Korean firms are building nothing in the United States. It is what kind of thing they are building.

A foundry manufactures other companies' designs. Packaging stacks and encases chips that already exist. Both companies' actual core is front-end memory fabrication — building DRAM and NAND on wafers — and that capacity remains overwhelmingly in Korea.

That empty column is precisely the target. And placing a front-end memory fab in the United States is a decision measured in tens of billions of dollars, categorically different from adding one foundry building or one packaging line.

One more piece sits underneath. China's CXMT was reported to have taken 10 percent of global DRAM share in the second quarter of 2026. When Samsung and SK hynix each fell more than 4 percent on September 2, Chinese HBM3E production news was among the drivers (see "Samsung Electronics and SK hynix fall 4% on September 2, 2026"). US containment of China and US pressure on Korean firms move on the same board.

3. The clause Korea is holding

Korea has a written basis already. Under last year's framework it committed 350 billion dollars of US manufacturing investment, and in exchange Korean chipmakers are to receive tariff rates no less favourable than competitors with equal or larger semiconductor trade volumes.

Read the clause carefully. It does not say "no tariff." It says "not treated worse than Taiwan or Japan." If Washington taxes everyone, Korea pays too — it just does not fall behind.

The September 4 remarks belong to that frame. The presidential office official said there are "various issues between South Korea and the United States, and they are sometimes affecting each other," adding that semiconductors are included in the investment discussions and that both governments are making efforts to prevent them from hindering each other.

Another sentence in the same briefing shows the structure: talks on Korea's plan to build nuclear-powered submarines had not progressed. Chips and submarines surfacing in one briefing is the point — several files sit on one table, and in that arrangement the chip terms can move on an outcome that has nothing to do with chips.

4. What is still open

• There is no rate. Effective date, product classification (how far "contains a chip" reaches), and exemption criteria are all unpublished. Only the design direction is settled.
• The "no less favourable" wording needs reading. Reports carry the substance, not the text. How the comparison set is defined and who adjudicates it determine whether the clause bites.
• The presidential office remarks are an unattributed briefing. Full text and context have not been released.
• The market is already trading this. On September 4, Samsung closed 2.20 percent higher at 255,500 won and SK hynix 3.20 percent higher at 1,647,000 won (see "KOSPI closes at 6,687.21 on September 4, 2026"). On August 28, foreign investors sold a net 1.7 trillion won on chip tariff news. The same file has been read as bullish and bearish within a week — which is what it looks like when nobody knows the answer yet.