The US-led joint naval exercise RIMPAC is underway off Hawaii, with China participating for the first time.
The US military hosts one of the world's largest maritime maneuvers every 2 years. Countries from the Pacific Rim and beyond take part.
The drills started on Thursday and will continue until August 1st.
US military officials say this year's RIMPAC will be the largest ever. More than 25,000 troops from 22 countries are taking part. The exercises include 55 ships and submarines, together with more than 200 aircraft.
US allies such as Japan, South Korea and Australia are participating.
The Chinese navy has sent 4 vessels. They are the missile destroyer Haikou, the missile frigate Yueyang, a supply ship and a hospital ship. China is scheduled to take part in bombardment and rescue exercises.
This year's RIMPAC comes amid growing sovereignty disputes in the South China Sea between China and neighboring countries Vietnam and the Philippines.
Chinese ships have also repeatedly violated Japanese territorial waters around the Senkaku Islands in the East China Sea. The islands are controlled by Japan, and claimed by China and Taiwan.
The international community is voicing concern over China's increasing maritime activities.
The United States wants to promote mutual trust with China through the drill. The goal is to help avert accidents or misunderstandings that could escalate into a crisis on the high seas.
Jun. 27, 2014 - Updated 00:43 UTC