CNN  —

Tariffs could add $900 million to Apple’s costs this quarter, Apple CEO Tim Cook said on Thursday, as he revealed the tech giant was shifting production of iPhones sold in the United States from China to India.

“Assuming the current global tariff rates, policies, and applications do not change for the balance of the quarter and no new tariffs are added, we estimate the impact to add $900 million to our costs,” he told a quarterly earnings call.

With some iPhone production having already moved to India in the past few years, Cook said he expected “the majority of iPhones sold in the US will have India as their country of origin.”

The announcement that Apple is diversifying its global supply chain beyond China in such a major way underscores the impact of US President Donald Trump’s astronomical 145% tariffs on the country.

About 90% of Apple’s production of the iPhone, its most profitable product, has remained in China, despite efforts to increase manufacturing elsewhere, according to financial services firm Wedbush Securities.

While the administration’s exemption of smartphones and other electronics containing semiconductors from “reciprocal” tariffs on China has spared iPhones from the harshest levies, products made in China still face a minimum 20% levy, according to Cook.

Apple’s stock fell nearly 4% in after-hours trading following the earnings call, reflecting investor concerns about the uncertain outlook posed by tariffs and supply chain instability.