China is slowing rare earth exports to the US again just weeks before Trump and Xi meet, which is bad news for American chipmakers, defense firms, and medical device companies.

• Some Chinese suppliers have simply stopped shipping rare earths to US buyers, afraid of punishment from Beijing.
• The freeze got worse after Beijing sanctioned a US supply chain watchdog group in early August, leaving suppliers scared to cooperate with American audits.
• Minerals used in weapons, aerospace, and chip making are the tightest, with prices hitting record highs.
• US exports of one key mineral, yttrium, are running at half of last year's level, and some American firms have waited over six months for Chinese export permits.
• Washington says Beijing is not honoring the deal struck in Busan, and has put it on the agenda for Xi's US visit on the 24th.

Outlook: Beijing is expected to loosen its grip on critical minerals around the Trump-Xi meeting to defuse US complaints, but the underlying leverage stays in China's hands.