Trump Backing for a Nippon Steel Deal Leaves Big Questions

The United States Steel Corp. Clairton Coke Works along the banks of the Monongahela River in Clairton, Pennsylvania.

Photographer: Justin Merriman/Bloomberg

After more than 17 months of lobbying and close-fought negotiations to secure control of United States Steel Corp., Japan’s Nippon Steel Corp. appeared on Friday to have received a presidential blessing.

Days later, however, investors, executives and diplomats are still unsure of what exactly the US president endorsed.