WASHINGTON, May 24 -- President Donald Trump on Friday said that US Steel will keep its headquarters in Pittsburgh as part of what he called a "planned partnership" that seemed to signal that he'll approve a bid by Japan-based Nippon Steel to make a big investment in the iconic American steelmaker, if not buy it outright.

Still, Trump's statement left it vague as to whether he is approving Nippon Steel's bid after he vowed repeatedly to block the deal to prevent US Steel from being foreign-owned, AP reports.

More recently, Trump suggested that Nippon Steel would invest in US Steel, not buy it, and one union official suggested Friday that the federal government will have a role in the company's management going forward.

But investors se...