On Tuesday the minister announced her department's plans for an increase in troop numbers, in order to cope with "new threats and growing responsibilities," the German newspaper Focus reported.
Van der Leyen's plans reportedly include the abolition of Germany's 185,000 troop limit, and the initial creation of 7,000 new jobs in the armed forces.
While the proposal has yet to be approved by the Bundestag, the German government has already approved a significant increase in the military budget over the next three years, which will increase from 34.3 billion euros to 39.2 billion euros by 2020.
Following the reunification of Germany, the country's armed forces were reduced from a combined 600,000 personnel, when the former East Germany's National People's Army became part of the Bundeswehr in 1990.
"It's not only a change in trend, in fact it represents a 180-degree turn in personnel policy," he said, adding that his union thinks the increase doesn't go far enough.
"Since the end of 2014 we have been in the red zone," said Wustner, and recommended that the armed forces increase by 15,000 soldiers and 4,000 civil employees by 2020.