Pro-Palestine activists travelled from as far as London for a demonstration at the UAV Engines factory in Shenstone, Lichfield on Tuesday.
Activists have said that UAV Engines, owned by Elbit Systems, produces motors for drones used in Gaza.
In the early hours of the morning the group scaled the walls of the building and climbed onto the roof before hoisting a Palestinian flag and daubed the frontage with red paint.
Staffordshire Police were called to the scene.
A spokeswoman for the force said: "Six people were arrested after police were called to reports of a protest at a factory site in Shenstone, Lichfield, shortly after 2am on Tuesday, February 23.
"Three men – a 69-year-old from Guilford, a 28-year-old from Bristol and a 23-year-old from London – and three women – a 31-year-old from London, a 37-year-old from London and a 28-year-old from Bristol – were arrested on suspicion of aggravated trespass, criminal damage and use of violence or intimidation on a person family or property to compel activity or abstention from lawful activity.
"Officers brought the demonstration to a safe and peaceful conclusion at around 4.45pm.
"All six remain in custody."