General Dynamics will lay off 31 workers from its Springboro plant, the company told the state this week.

The workers at the company’s 200 S. Pioneer Blvd. plant will be terminated permanently beginning in mid-October, the company said in a letter to the Ohio Department of Job and Family Services.

“This employment action is due to a sharp decline in work from the facility’s principal customers,” Ray Steen, General Dynamics human resources director, wrote in a letter dated Aug. 13.

The company laid off 29 workers from the same plant in February. Those layoffs were attributed to a delay in an order for mortar fins from the U.S. Army. The 240,000-square-foot plant makes rocket motor tubes for the U.S. Army’s Hydra 70-air-to-ground rockets. The plant also produces liners and cartridges for 40mm ammunition rounds and components to its 60mm-120mm mortar rounds.

General Dynamics acquired the plant in August 2012. The acquisition was seen as a way for General Dynamics to consolidate its supply chain. The Springboro plant — which had long served General Dynamics — can perform metal forming, heat treatment, machining and coating, all under one roof.

The February layoffs were the first round of layoffs at the plant after General Dynamics bought it. After those layoffs, the employee count stood at about 135.

A company spokesman asked for time before answering questions.

General Dynamics announced in July that it will merge its Armament and Technical Products division into its Ordnance and Tactical Systems Division. The Springboro plant is part of the former division. It wasn’t clear what impact the merger would have on the plant.

The consolidation will result in the closing of the Charlotte, N.C., headquarters of the ATP division by the end of the year, the company has said.