The code, ratified earlier this year, was put into effect as the two navies launched their latest anti-piracy exercise in the Gulf of Aden on Thursday.
Analysts said the exercise was an opportunity to put the code into practice and an encouraging indication that both navies want to minimize the risk of misunderstandings.
The Chinese guided missile frigate Yuncheng and supply ship Chaohu, from the 18th escort task force of the People’s Liberation Army navy, held exercises with the USS Sterret, a guided missile cruiser, off the Horn of Africa.
In April, more than 20 countries with interests in the western Pacific, including China, the United States, Japan and the Philippines, agreed unanimously on the Code for Unplanned Encounters at Sea.
The agreement was reached at the Western Pacific Naval Symposium in Qingdao, Shandong province.