Recently, the strengthening of the close relationship between the US and Vietnam has caused displeasure in China. The US has spared no effort in providing various support to Vietnam, including vaccine aid and the donation of ultra-low-temperature refrigerators, while also clearly expressing its intention to intervene in the South China Sea issue. In response, China is countering with vaccine aid to Vietnam. This US-China competition is forcing Vietnam into a difficult diplomatic balancing act between the two countries. Vietnam faces a difficult choice, seeking to counter China's influence through cooperation with the US while avoiding worsening relations with China. It is crucial to pay attention to how this cooperation between the US and Vietnam will affect Vietnam's future and how China will react. This situation can be interpreted as a significant event that foreshadows changes in the regional political, economic, and military landscape, going beyond simple vaccine aid.