Translate the following English sentence to French:
"However, the responsible authorities of the Western countries need to make it clear that, once the mission of the United Nations committee has been successfully completed, the embargo will be lifted and normal trade relations will be able to be resumed."
Il faut cependant que les autorités responsables des pays occidentaux disent haut et fort que, une fois la mission de la commission des Nations unies couronnée de succès, l'embargo sera levé et des relations commerciales normales pourront reprendre.