China replaces foreign minister Qin Gang with Wang Yi at ASEAN summit due to illness

Qin Gang will not attend ASEAN summit in Indonesia due to illness; former minister Wang Yi will represent China instead.
Qin Gang has not been seen publicly for over two weeks; no details given about his health.
Wang Yi recently suggested forming alliance between China, Korea and Japan to counter Western influence.
China seeking to expand influence in Southeast Asia to challenge U.S.; aggressive South China Sea claims have limited progress.
ASEAN foreign ministers' meeting aims to build trust, consensus and promote regional peace and prosperity.