The trade war between the United States and China since 2008 has opened strategic opportunities to increase the economic market in ASEAN countries. This research aims to answer whether the trade war led to an oligopoly or a systemic market structure as a strategy for increasing demands, especially in ASEAN countries. The research exploration refers to trade data between Indonesia and ASEAN at the start of the 2018 US-China trade war and compares it with the latest data for 2020. This research uses the Results Index of C5 Analysis of ASEAN Trading Partner Countries and the Herfindahl–Hirschman index to examine trade between China, America, Japan, South Korea and Taiwan in the ASEAN economy. Findings, in a way, empirically shows that the Results Index of C5 Analysis of ASEAN Trading Partner Countries before and after US-China trade made market concentration moderate and caused an increase in the value of C5 Analysis Results of ASEAN Trading Partner Countries. Discounts on Herfindahl–Hirschman the index needs to pay attention to import players in ASEAN before the trade war. However, after the trade war, there was an increase in the Herfindahl–Hirschman index, which has a trend toward a collusive oligopoly market structure.