The role of international collaboration in the 21st-century scientific and technological Chinese emergence has been documented, especially with the US. We found that this collaboration dominates the CS. Nonetheless, its overall contribution is modest, representing less than 2% of all discoveries of chemicals (Figure ). China-US collaboration grew over time, peaked in 2017 and ever since has been volatile (Figure ). This partnership increased hand in hand with the increment of bilateral agreements enacted during the Obama administration (2009-2017). Likewise, the post-2017 perturbation is presumably related to the 2018 China initiative, championed by the US government. Notwithstanding the China-US collaboration, over 90% of China's contribution to the CS was achieved by domestic teams operating independently. In contrast, the US has seen a decline in solo contributions, which exceeded 95% between 1996 and 2006 but sharply decreased to less than 80% of its participation in the CS expansion (Figure ). The drop of US solo contributions has been counterbalanced by an increase in international collaboration (Figure ), in particular with China.