Trucks were at a MAN repair facility and not at a military facility.
German Source (with additional info): https://www.mdr.de/nachrichten/thueringen/mitte-thueringen/erfurt/bundeswehr-brandanschlag-russland-ukraine-ermittlungen-100~amp.html
(edit) some translated excerpts:
The Bundeswehr vehicles damaged and destroyed in an arson attack in Erfurt at the weekend were not intended for delivery to Ukraine. A spokeswoman for the Federal Ministry of Defense told MDR Investigativ on Friday when asked about this. The six trucks belonged to two Bundeswehr units in Erfurt and Bad Frankenhausen and had been handed over to MAN for maintenance. With the handover, the company is responsible for the condition of the vehicles and therefore also for their safety.
During the attack on the night of June 21-22, five trucks were completely destroyed and one was slightly damaged. They were UTF 3 and 6 trucks, an internal Bundeswehr designation meaning unprotected transport vehicle. Such vehicles are not additionally protected by armor. Trucks of this type are “the workhorse of the troops”, said the ministry spokeswoman. According to MDR information, the trucks belong to Supply Battalion 131 in Bad Frankenhausen and IT Battalion 383 in Erfurt.
This weekend's attack in Erfurt is the second of its kind on the MAN site in the north of Erfurt. On June 1, 2024, six military vehicles were also set on fire and damaged there. Three of these vehicles belonged to the Bundeswehr, the other three to the Singapore armed forces. According to MDR information, there are indications of three possible suspects in this case. The spokeswoman for the public prosecutor's office in Erfurt said that the investigation into this case is currently being conducted against two suspects. The investigation is also still ongoing.
