During this period, there were several significant foreign policy challenges and achievements. Let's examine them in detail:

1. End of the Cold War:
- The most significant achievement during this period was the end of the Cold War between the United States and the Soviet Union.
- This led to a significant shift in global dynamics and allowed for greater cooperation and diplomacy between nations.
- The collapse of the Soviet Union resulted in the emergence of new nations, which created both opportunities and challenges for foreign policy makers.

2. Globalization and Economic Integration:
- The period saw an increased focus on economic integration and globalization.
- Many countries pursued liberal economic policies and entered into trade agreements to promote economic growth.
- The establishment of the World Trade Organization (WTO) and regional trade blocs like the European Union (EU) and ASEAN further facilitated economic cooperation.

3. Rise of Non-State Actors:
- The emergence of non-state actors such as terrorist organizations posed a significant challenge to foreign policy makers.
- The September 11, 2001 terrorist attacks in the United States prompted a shift in global security policies, with a greater emphasis on counter-terrorism efforts and cooperation between nations.

4. Humanitarian Interventions:
- The period witnessed several humanitarian crises, such as the conflicts in Rwanda, Kosovo, and Sudan.
- Humanitarian interventions became a key foreign policy challenge, with the international community grappling with how to respond to these crises while respecting national sovereignty.

5. Nuclear Proliferation and Arms Control:
- Nuclear proliferation remained a major concern during this period.
- Several countries, including North Korea and Iran, pursued nuclear programs, leading to increased tensions and the need for diplomatic efforts to prevent further proliferation.
- The signing of the Joint Comprehensive Plan of Action (JCPOA) with Iran in 2015 was a notable achievement in curbing nuclear proliferation.

6. Climate Change and Environmental Cooperation:
- Climate change emerged as a significant challenge during this period, requiring global cooperation and coordination.
- The signing of the Paris Agreement in 2015 marked a major achievement in international efforts to combat climate change.

7. Regional Conflicts and Peacekeeping:
- The period saw numerous regional conflicts, such as the wars in Afghanistan and Iraq.
- Peacekeeping efforts by the United Nations and regional organizations played a crucial role in managing these conflicts and promoting stability.

In conclusion, this period witnessed both significant challenges and achievements in foreign policy. The end of the Cold War, economic integration, and increased cooperation between nations were notable achievements. However, the rise of non-state actors, humanitarian crises, nuclear proliferation, and climate change posed significant challenges that required diplomatic efforts and global cooperation.