1-173. Transitions mark a change of focus between phases or between the ongoing operation and execution of a branch or sequel. Shifting priorities between offensive, defensive, and stability tasks also involves a transition. Transitions require planning and preparation well before their execution so that a force can maintain the momentum and tempo of operations. A force is vulnerable during transitions, and commanders establish clear conditions for their execution. Commanders identify potential transitions during planning and account for them throughout execution. Commanders should appreciate the time required to both plan for and execute transitions. Assessment ensures that commanders measure progress toward such transitions and take appropriate actions to prepare for and execute them.