U.S. President Donald Trump said on Friday that Chinese President Xi Jinping had agreed to restart the flow of rare earth minerals and magnets to the United States.

But there was a discrepancy in the two sides’ statements after the Trump-Xi call on one of the most contentious issues: rare earths, which are needed to make all kinds of advanced technologies and are produced almost entirely in China.

Politicians said the call between the two leaders, which focused on trade, had ‘made us very anxious’ about the implications for the island.