The Boring Co, a firm owned by Elon Musk, has asked the White House to exempt it from tariffs for some Chinese-made tunnel boring machine components.
Reuters cited the July 31 letter by the Boring Co as saying that the tariffs may substantially delay a planned tunnel between New York and Washington.
The letter, published on a US government website, added that Boring Co needs "limited parts from China in the near-term for use in a small number of tunnel boring machines" and that those parts are "readily available only from China."
The New York-Washington tunnel is part of the Boring Co's plans to ferry passengers on autonomous electric vehicles carrying up to 16 passengers at about 120 miles (193 kilometers) per hour.
Beijing has responded with tit-for-tat measures, targeting US LNG among other American exports.
In July, Washington introduced high duties against $34 billion in Chinese imports, in a move that was preceded by US President Donald Trump confirming in mid-June that a 25-percent tariff would be imposed on $50 billion in Chinese goods.