U.S. Role in South China Sea Tensions: China vs. Philippines

Recently, Chinese coast guards and the Philippine military clashed in the South China Sea. While Southeast Asian nations aim to establish a Code of Conduct for joint resource development in the region, why is the Philippines closely aligning with the U.S., exacerbating regional tensions? With the U.S. entangled in multiple global issues, would it really back the distant Philippines in a serious conflict with China?