A Times investigation found that Ms. Chao has repeatedly used her connections and status in China to help Foremost, which benefits from industrial policies in Beijing that are at the heart of diplomatic tensions with Washington.

Ms. Chao has no stake in Foremost, but she and her husband, Senator Mitch McConnell of Kentucky, have received millions of dollars in gifts from her father, James, who ran the company until last year. Read the takeaways from our investigation.

Response: Ms. Chao declined to be interviewed, but in a written statement she affirmed her family’s commitment to the U.S. A Transportation Department spokesman said there was no link between Ms. Chao’s actions as secretary and her family’s business interests in China.

Background: The editors who lead our investigations team answered questions about how The Times decides which projects to pursue.