Final answer:
North Korea is the Communist Asian country that conducted its first nuclear test in October 2006, creating a concerning international situation due to the potential threat posed by the country's nuclear capabilities.
Step-by-step explanation:
The Communist Asian country that had its first nuclear test in October 2006 is North Korea. This event marked a significant moment in international relations, as the nuclear test was the result of decades of development within the isolated country of the Democratic People's Republic of Korea (DPRK). Despite the hopes for denuclearization, North Korea's leadership believed that possessing nuclear weapons would ensure the country's survival, especially after witnessing the fates of other regimes post-Cold War.
The United States, alongside South Korea and Japan, expressed grave concerns given North Korea's history of instability and the potential threat of nuclear weapons being used in the region. This test was a pivotal point in the global effort to limit the spread of nuclear armaments and the ongoing struggle to curtail North Korea's weapons program.