A North Dakota City Attracted a Corn Mill. Then Came Questions About Its Chinese Owners.

At the request of the F.B.I., the meeting was held behind closed doors. Some residents who wanted to hear what the agency had to say held a protest. And though Grand Forks officials said they were left with the impression that there were no national security concerns about Fufeng, they acknowledged that the F.B.I. would not confirm that explicitly, leaving critics of the project unsatisfied.

Grand Forks is not a moribund city in desperate need of work.

Unlike in Maine, where Chinese investors resurrected an old mill a few years ago, or Ohio, where a Chinese glassmaker opened up shop in an abandoned General Motors factory, there is no jobs crisis in Grand Forks. The city is growing, the metro unemployment rate is below the national average, and employers are hiring. In addition to jobs in agriculture and the military, residents work in manufacturing or at the University of North Dakota, known for its aviation program and powerhouse hockey team.

Still, Mr. Bochenski, the mayor, has stressed the economic benefits of Fufeng for his city, where 18 percent of residents live in poverty, well above the national rate. Farmers have welcomed the project as a new place to sell their corn, which grows in abundance in the fertile soil along the Red River. And Governor Burgum, a former businessman, has repeatedly stood by the project.

“With Fufeng in Grand Forks, it will be North Dakota — not China — that reaps the benefits of the jobs, facilities, economic activity and tax revenue associated with processing the corn,” a statement from the governor said.

It is fairly common for a Chinese company to do business in the United States, and for an American company to do business in China.

But as diplomatic relations have frayed, American officials, especially Republicans, have questioned whether the United States has grown too close to China economically, and whether seemingly innocuous Chinese investments could be used for nefarious purposes.