Final answer:
After a "go" decision in Phase 3 of international planning, the next step is typically the Implementation and Learning Phase, where the plan is executed and adapted based on ongoing learning and feedback.
Step-by-step explanation:
Once a "go" decision has been made in Phase 3 of the international planning process, it is most likely that the next step would be the Implementation and Learning Phase. This phase involves taking the necessary actions to execute the plan, which may include allocating resources, initiating set projects or policies, and beginning the process of integration into the target international markets or systems. This phase also includes monitoring and adapting to any new developments or feedback, thereby ensuring a continuous learning process to improve the efficiency and effectiveness of the plan's implementation.