Today Boeing Co. presents its first 787 Dreamliner jet—a passenger-friendly, light-body aircraft that uses less fuel—to All Nippon Airways Co. But the delivery ceremony likely will have a bittersweet undertone for Boeing executives in the wake of documents released Friday that exacerbate the company’s troubles with the National Labor Relations Board (NLRB).

This past Friday, Boeing’s union released internal documents that it claims reinforce the NLRB’s case charging the airline manufacturers with illegally transferring work on the 787 Dreamliner from a union worksite in Everett, Wash., to a new, nonunion facility in Charleston, S.C., to punish union members for past strikes. The board wants to force the company to relocate manufacturing of the 787 Dreamliner back to Washington.

According to the documents, Boeing officials worried that the South Carolina facility, also known as “Project Gemini,” was a high-risk plan. Building the new plant for more than $750 million would exceed the costs of expanding the Washington facility. 

“The Project Gemini documents prove what we’ve suspected all along—that Boeing moved to Charleston to punish our members for exercising their union rights,” International Association of Machinists Spokesperson Connie Kelliher said on Friday.

Boeing denies that its decision to open the Charleston facility was a retaliatory act. It has vowed to fight the NLRB’s proposed relocation order back if the case reaches the Supreme Court. The case is ongoing.