Final answer:
The role not included in peacekeeping missions is withdrawing humanitarian assistance. Peacekeeping involves re-establishing state security and governance structures while providing aid, not removing it.
Step-by-step explanation:
You have asked which role is not typically included in peacekeeping missions that involve state-building. Among the options provided, the role that is exceptionally not part of peacekeeping missions is d) Withdrawing humanitarian assistance. Peacekeeping has often been tied with various state-building roles, such as a) Re-establishing military forces, b) Building political institutions, and c) Re-establishing police forces. However, withdrawing humanitarian assistance is not one of these roles; in fact, peacekeeping missions work towards promoting justice and stability, which includes providing necessary humanitarian aid.
Peacekeeping efforts focus on fostering peace negotiations, supporting immediate needs through aid, and helping to restore a country to a functioning state for the safety of its citizens. This includes diplomacy, economic support, and maintaining armed forces for security as necessary, not withdrawing support.
Furthermore, various international treaties and commitments underline the importance of humanitarian assistance in the efforts of the United Nations and other organizations to maintain international system welfare and protect human rights, which contradicts the withdrawal of such support.