Ford (F) stock was volatile a day after the White House questioned its strategy of using Chinese partners. Ford responded forcefully after the bell, hinting at possible behind-the-scenes drama.

In a letter to Ford CEO Jim Farley on Tuesday, Transportation Secretary Sean Duffy expressed "profound concern" over Ford's strategic decisions regarding "manufacturing integrity, supply chain exposure, and reliance on technologies of foreign adversaries," specifically China.

Duffy's main concerns were Ford's use of Chinese battery-maker CATL tech in its battery factory in Marshall, Mich., Ford's joint factory with Geely in Spain, and Ford's ongoing talks with BYD for hybrid vehicle components, as well as a supposed plan put forth by Farley to facilitate Chinese joint ventures in the US.

Ford stock fell in Tuesday's trade before recovering slightly on Wednesday.

Interestingly, Duffy also mentioned a delayed reshoring of Lincoln Nautilus production to the US from China, which is a major focus of President Trump and his controversial tariff plan.

Ford didn't pull punches with its response to Duffy's letter. "Secretary Duffy's head-scratcher of a letter comes a week after [the] White House touted the very same job-creating Michigan project he's questioning," Ford chief communications officer Mark Truby blasted on X.com , linking to Ford's official response .

Duffy's letter was a "wrongheaded attempt to capture headlines at the expense of a company that has done more for American manufacturing than virtually any other in the nation's history," Ford opened with its response, adding that while other rivals and foreign competitors relied on importing vehicles in the US, Ford was "doubling down" on US production.

Part of that US production is the battery plant in Michigan, which Ford sought to clarify again: "The CATL arrangement is a limited technology-licensing and services agreement, not a joint venture or foreign-owned manufacturing operation. Ford owns the plant, controls the operation and employs the workforce."

President Trump speaks to Ford executive chair Bill Ford, Treasury Secretary Scott Bessent, Ford CEO Jim Farley, and Ford River Rouge plant manager Corey Williams during a tour of the Ford River Rouge complex on Jan. 13, 2026, in Dearborn, Mich. (AP Photo/Evan Vucci) · ASSOCIATED PRESS

Ford also called Duffy's assertion of a delayed reshoring of Lincoln Nautilus production "misguided," adding that the company is working with White House administration officials to bring back assembly to the US. Ford also cited Commerce Secretary Howard Lutnick praising that decision just last month.

Finally, Ford denied that Farley had pushed a framework to facilitate Chinese joint ventures in the US.

Add it all up, and the back-and-forth letters paint an acrimonious relationship between CEO Jim Farley and the White House, surprising given that Farley and Trump appeared to have a decent relationship. Trump visited a Ford plant earlier this year, and Farley has appeared at various events at the Oval Office.