How did the European system of spheres influence on china threaten us interests?

The European system of spheres of influence in China threatened U.S. interests by undermining American access to trade and investment opportunities in the region. As European powers carved out exclusive territories and privileges, the U.S. risked being marginalized in the growing Chinese market. This situation prompted the U.S. to advocate for an "Open Door Policy" to ensure equal trading rights for all nations and to prevent any single power from dominating China, thereby protecting its economic interests and promoting stability in the region.