The bond market went haywire this week. Here's why that's a warning for the US and Trump.

Traders working on the floor at the New York Stock Exchange.

Brendan McDermid/REUTERS

• Intense volatility in the bond market this week helped drive the president to partly pause the trade war.
• A sell-off of US Treasurys pushed yields to their highest level since January.
• The spasm in the Treasury market—normally a safe haven—is a warning for the US and Trump.

The bond market sent a warning to Donald Trump this week.

A sharp sell-off in Treasurys—unusual...