Now in its 38th year, Cobra Gold is one of the largest military exercises in Asia, bringing thousands of forces from the United States, Thailand and other countries together for 11 days of training on Thai shores.

This year's drill includes some 2,000 US Marines, 1,000 US soldiers and hundreds from the country's Navy and Air Force.

On Saturday US, Thai and South Korean forces descended on Namsai beach in Chonburi province in a joint drill intented to simulate securing the territory.

Captain Melvin Spiese told AFP the goal was to "bring power from ship to shore" and be ready for "any kind of future crisis we might need to respond to with our Thai counterparts."

Helicopters buzzed overheard and fighter jets roared across the skies.

Cobra Gold exercises span air, land and sea and feature a jungle survivalist session where participants take turns drinking blood from a severed cobra and snacking on insects and scorpions.

Singapore, Japan, Indonesia and Malaysia also took part in the war games.

A 2014 army coup in Thailand tested ties with Washington and the kingdom tilted towards China with high-profile arms buys.

But US military sales continued and the two countries have upped their engagement under US President Donald Trump, who has stepped back on human rights issues and invited junta chief Prayut Chan-O-Cha to the White House.

Prayut, who led the 2014 coup, is standing for prime minister in elections set for March 24.