The Franco-Belgian agreement stipulated Belgium was to mobilise if the Germans did, but what was not clear was whether Belgium would have to mobilise in the event of a German invasion of Poland.
Den fransk-belgiske aftale indeholdt en bestemmelse om at Belgien skulle mobilisere i tilfælde af at Tyskland mobiliserede, men det stod ikke klart om Belgien skulle mobilisere i tilfælde af at Tyskland invaderede Polen.