Amid 'challenging' times, Thailand and U.S. start scaled down drills

NAKHON NAYOK, Thailand (Reuters) - The United States said on Monday its relationship with longtime ally Thailand was going through a "challenging" period as the two sides began a major military exercise, scaled down over Washington's concerns about the junta leadership.

Cobra Gold, the largest military exercise in the Asia-Pacific, has been held annually in Thailand for more than three decades, but the United States scaled the drill back this year after sanctioning Bangkok for last year's coup.