After a round of talks in Geneva last month, the United States and China will sit down at the negotiating table in London on Monday to attempt to preserve a fragile truce on trade, despite simmering tensions.

Mr. Trump said in a post on Truth Social that his call with Xi Jinping, China’s top leader, had focused entirely on the trade relationship between the nations, which has soured in recent months in a dispute over the export of critical minerals used in an array of industries.

President Donald Trump held a long-awaited phone call Thursday with China’s Xi Jinping, a person familiar with the matter said, as the two leaders tussle over trade policy.