Saturday's drills saw almost 1,200 marines and soldiers from Thailand, South Korea and the United States, backed by amphibious vehicles, storming ashore a beach in Sattahip, Chonburi Province.
Relations between Washington and the Thai government were strained following 2014's military coup in Thailand, and US involvement in Cobra Gold was scaled down.
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But, with a confident China flexing its muscles in the region, the US has rebuilt its involvement in an attempt to counter Beijing's growing influence.