The antonyms for the term "base operation" could include:
1. Complex maneuver - this implies a highly coordinated and intricate plan of action, quite opposite to a base operation that is usually routine and simplistic.
2. Advanced operation - This can refer to an operation that involves highly specialized and sophisticated tools or techniques, unlike the base operation that is simple and basic.
3. Elaborate task - This term indicates a comprehensive and intensive task that may involve multiple stages, unlike the base operation that is usually a single, straightforward task.
4. Intricate mission - This term suggests a highly detailed and complicated mission, which requires a more significant level of planning and effort, unlike a base operation that is usually uncomplicated.
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