US-Korea-Japan leaders’ meeting, BRICS South Africa summit, Middle Power in Global Politics

US President Joe Biden hosted ROK President Yoon and Japan PM Kishida in Camp David for a trilateral summit meeting that seeks to deepen its security partnership to strengthen trilateral deterrence and contribute to long-term balance of power in East Asia and in the Indo-Pacific.  BRICS summit in South Africa added six new members to this economic forum of the non-G7 countries.  Are these evidence of greater agency of middle powers in the context of the US-China strategic competition? Why are the middle powers taking the initiative?  Can the middle powers be considered as another pole between the two poles of US and China?