Sound like someone does not want to pay their full NATO dues.
Belgium is worried about the EU disintegrating. The EU capital is Brussels, Belgium - which means if the EU tanks, Belgium loses all their prestige, power, influence, graft opportunities, income from EU orgiastic parties, etc., and go back to their main claim to international fame being food and their major influence on world events being ‘Germany’s traditional invasion route to France.’
The US equivalent to what would happen to Belgium in the event of the EU disintegrating would be a city in the US that formerly was wealthy because all the railroads went through it discovering that the then-new Interstate highway wasn’t going to be going anywhere near it. It’ll start withering to unimportance and become a backwater Podunkville in short order.