The most effective way for the CIO to ensure the IT management team is held accountable for the delivery of the plan is to revise the managers' performance goals to include key objectives that are aligned with the IT strategic plan. This way, the managers will have clear and measurable targets that reflect their contribution to the IT strategy and vision. The CIO can also monitor and evaluate the managers' progress and performance based on these goals, and provide feedback, recognition, or improvement actions as needed.
The other options are not the most effective way for the CIO to ensure the IT management team is held accountable for the delivery of the plan. Updating the IT balanced scorecard with key objectives is a good practice, but it does not directly link the objectives to the managers' individual responsibilities and incentives.
Enforcing disciplinary action for managers if the plan is not delivered is a negative and punitive approach, which may demotivate and discourage the managers from pursuing the plan. Providing management training on IT strategic objectives is a helpful initiative, but it does not specify how the managers will be assessed and rewarded for achieving the objectives.
For more information on IT strategic planning and accountability, you can refer to these web sources:
IT Strategic Planning: A Step-by-Step Guide
How to Hold Your Team Accountable
IT Governance - CIO Wiki