Taiwan has told Washington that its proposal to move 40% of Taiwan’s semiconductor supply chain to the United States is “impossible” to implement, Taiwan’s top tariff trade negotiator said in an interview.

talking about a Broadcast on local television On Sunday, Vice Premier Cheng Lijun said she had made it clear to Washington that the semiconductor ecosystem China has built over decades cannot simply be relocated.

The comments countered the homegrown goals laid out by U.S. Commerce Secretary Howard Lutnick in an interview with CNBC in January shortly after the signing of the latest U.S.-Taiwan trade deal.

Down tradeTaiwan government promised $250 billion direct investment Taiwanese tech companies have been promised an additional $250 billion in credit to expand production capacity in the United States in return Higher duty-free export quotas Their chips go to the United States

Lutnick said Taiwanese chip companies that do not produce in the United States could face 100% tariffs.

TSMC, the world’s leading contract chipmaker and producer of the most advanced semiconductors, has been working to better align with U.S. policy interests.

The company has invested more than $65 billion in U.S. manufacturing in recent years and plans to expand that to $165 billion, producing chips for U.S. customers Apple and Nvidia. These investments leverage grants under the America’s CHIP and Science Act.

Semiconductor analysts generally agree with Cheng’s assessment that Washington’s most ambitious homegrown plans are unfeasible because of the difficulties of relocating such an advanced supply chain.

Analysts and industry officials point to Taiwan’s deeply integrated semiconductor ecosystem, U.S. labor shortages and rising costs as some of the major obstacles.

Geopolitical analysts also point to the so-called “Silicon Shield” theory, which holds that Taiwan’s key role in global chip supply makes it a strategic priority for the United States to maintain its autonomy to deter potential Chinese aggression. Beijing claims sovereignty over the democratically governed island.

This silicon shield may further prevent Taiwan from moving supply chains overseas.

Taiwanese authorities have implemented a policy that requires TSMC’s overseas factories to use technology at least two generations behind the cutting-edge technology deployed in Taiwan, a policy commonly known as the N-2 rule.

The Commerce Department did not immediately respond to a request for comment on Cheng’s statement.

As part of the latest trade deal, Washington said it would cut tariffs on most Taiwanese goods from 20% to 15% and exempt generic drugs and raw materials, aircraft parts and natural resources that are not available domestically from tariffs.

TSMC shares rose 2.75% in Taiwan on Tuesday.

—CNBC’s Matthew Chin contributed to this report.