This is an bi-annual exercise. The first RIMPAC was held in 1971. It includes this year Chinese ship (054A)
Australia, Canada, and the US have participated in every RIMPAC since then. Other regular participants are Chile, Colombia, France, Indonesia, Japan, Malaysia, the Netherlands, Peru, Singapore, South Korea, Thailand, and the UK. The Royal New Zealand Navy was frequently involved until the 1985 ANZUS nuclear ships dispute, but has taken part in recent RIMPACs such as in 2012, 2014 And 2016.
Several observer nations are usually invited, including China, Ecuador, India, Mexico, the Philippines, and Russia, who became an active participant for the first time in 2012. While not contributing any ships, observer nations are involved in RIMPAC at the strategic level and use the opportunity to prepare for possible full participation in the future.
https://en.wikipedia.org/wiki/Exercise_RIMPAC