Conflicting signals from the Trump administration over proposed restrictions on foreign investment in U.S. technology companies, along with news that recently imposed import tariffs are starting to disrupt supply chains, sent global stock markets tumbling on Monday. Proposed restrictions on foreign investment in U.S. technology would not just be confined to China, according to U.S. Treasury Secretary Steven Mnuchin. The forthcoming restrictions would apply “to all countries that are trying to steal our technology,” he said.

The U.S. Treasury is due to issue its recommendations on Chinese investment restrictions on Friday. Late Monday White House trade and manufacturing adviser Peter Navarro sought to downplay Mnuchin’s remarks, telling CNBC television that the restrictions on investments in U.S. technology companies would just target China. Benchmark Wall Street stock indexes suffered their worst losses in two months on Monday, while safe-haven Treasury debt yields fell. U.S. ...