All aircraft require weapons integration, whether they arrive at the point of sale in their weaponized state or not. Indigenously produced WMD will probably differ from their foreign counterparts. A proliferant must discover, on its own, the idiosyncrasies of the interaction of a weapon and the aircraft that carries it to plan for these modifications. For example, bomb bay doors opening at certain velocities sometimes cause severe aircraft vibration. Similarly, once the bomb bay doors are open the airflow around the weapon may cause it to vibrate uncontrollably.
Wind tunnels assist a proliferant in estimating the extent of any needed modifications.
The weapons, on the other hand, may need to undergo significant refinements, depending on the ultimate intentions of the country. Some simple standoff weapons, such as glide bombs, may provide a proliferant a unique penetration capability. The girth of the weapon or its aerodynamic surfaces may create a release problem that forces the proliferant to consider designing folded aerodynamic surfaces. However, a glide bomb is both more accurate than an ordinary gravity bomb and has a greatly reduced RCS compared to the aircraft which drops it, thus solving many of the problems of penetration. To hit in the vicinity of the target, even a large area target such as a city, the post drop vehicle may need an autonomous guidance and control unit.