BHP Billiton had already riled Chinese steel mills with its 2008 bid to take over Rio Tinto, though BHP Billiton later dropped its offer in the face of stiff global opposition among competition regulators. BHP Billiton upset the mills again in 2009 with a proposed iron ore joint venture with Rio Tinto, a deal that also floundered over anti-competition concerns. Between those two failed attempts to forge a BHP Billiton-Rio Tinto alliance, Chinese state-owned metals conglomerate Chinalco proposed a $23 9 billion partnership with Rio Tinto, which Rio Tinto initially accepted, but later rejected.