The biggest US force in years joined an annual military exercise in Thailand on Tuesday despite controversy over the Thai junta's invitation to neighboring Myanmar's army, which has been accused of ethnic cleansing.The United States scaled back attendance at Cobra Gold, Asia's largest multilateral military exercise, after a 2014 coup in Thailand. But relations between the junta and the United States have improved under President Donald Trump.The presence of the 6,800 US personnel - nearly double last year's number - was a demonstration of America's continuing muscle in a region where China is growing ever more powerful.The Cobra Gold military exercise has been held for more than three decades. This year's Cobra Gold will be attended by some 11,075 personnel from 29 countries."This exercise is the largest multilateral exercise in the Indo-Pacific region. It speaks to the commitment of the US in the region," Steve Castonguay, a spokesman for the U.S. Embassy in Bangkok, told Reuters.