Which of the following is NOT a key to successful operations?

Occupying enemy strongholds is generally not considered a key to successful operations in the same way that the other options are, which focus on a more strategic and tactical approach. Successful military operations often hinge on exploiting the enemy's weaknesses and vulnerabilities, forcing them into unfavorable situations, and isolating them from their logistical support. These strategies aim to disorient and diminish the enemy's combat effectiveness.

In contrast, merely occupying strongholds does not guarantee success. Strongholds can be well-defended and can potentially lead to costly engagements without necessarily yielding strategic advantages. The focus in effective military operations is generally on maneuvering the enemy and disrupting their capabilities rather than capturing specific positions, especially if those positions are heavily fortified or strategically irrelevant to the overall mission. This is why the concept of merely occupying a stronghold does not align as closely with the principles of successful military operations that emphasize adaptability and exploiting opportunities.