Alliant Techsystems and Orbital Sciences said Tuesday they plan to merge in a $5 billion deal, creating an aerospace and defense company called Orbital ATK.

Virginia-based Alliant, best known as ATK, operates the federal Lake City Army Ammunition Plant in Independence, which has more than 2,400 employees.

In 2013, ATK bought Overland Park-based Bushnell Group, which at the time of the sale had about 1,100 employees, including about 300 here.

ATK said in the announcement that it would essentially split into two companies. Its defense and aerospace work will combine with Orbital Sciences. It will also create a separate company for its outdoor sports business, which includes Bushnell and its product line. The name of the sporting group has not been determined.

ATK and Orbital have been discussing the merger for about six months, said Mark DeYoung, ATK’s chief executive and president.