Answer:
The answer is: French troops invaded the Ruhr.
Step-by-step explanation:
When Germany failed to pay reparation a six-month was given. When Germany failed to pay reparations even in that time France invaded the important Ruhr region of Germany and occupied it.
Belgium was also involved in the occupation which last for nearly two years. The aim was to occupy the region until Germany agreed to pay the Reparations again. However, the occupation had a very poor impact on the economy resulting in Hyperinflation in Germany.