By David Brunnstrom, Idrees Ali and Ju-min Park WASHINGTON/SEOUL (Reuters) -When South Korean President Lee Jae Myung meets U.S. President Donald Trump next week for their first summit, he will be asked to pay more for the upkeep of American troops on the peninsula during talks set to be dominated by security issues and China.

South Korea's President Lee Jae Myung faces a pivotal foreign policy test barely two months after taking office, with back-to-back summits in Tokyo and Washington that reflect the wider struggle of U.