EU9, has become a vital part of the EU. This group entered the EU in its 3rd growth phase in 2004, injecting new ideas and cultural diversity into the Union's mix.

The members of EU9 include Malta, Estonia, Slovenia, Slovakia, Czech Republic, Hungary, Latvia, Lithuania, and Poland. These countries have made significant contributions towards advancing the goals of the European Union.

Therefore, comprehending the responsibility EU9 holds in the European Union is required for any study relating to international relations, politics, or European economics.

From their entry, the members of EU9 have added substantially towards shaping the policies of the European Union. Their geographical location offers vital strategic edges, rendering them a vital part of the defense and security strategies of the EU.

Additionally, these nations have tremendously contributed to the European Union's economic strength. The EU9 nations' rapid economic growth and willing integration into the European market has resulted in increased trade among other EU states.

The social contribution of the EU9 is equally significant. These countries bring profound historical backgrounds, individual cultural practices, and varied languages, thereby enhancing the diversity of the website EU.

The inclusion of EU9 has also influenced the political scene within the EU. With their presence, the power dynamics have shifted, with new coalitions and alliances developing.

In conclusion, the parts played by the EU9 nations are substantial. From economic influence to cultural richness, and from security strategies to political dynamics, EU9 has strengthened the European Union's core strength. As such, an comprehensive understanding of the EU9 is vital to fully grasping the details of the European Union.