Whether President-elect Donald Trump goes through with a deployment of a U.S. anti-missile system in South Korea will be a key indicator to how political ties unfold with China, sources with ties to the leadership in Beijing said.

Beijing also kept a close eye on Trump's meeting Thursday with Prime Minister Shinzo Abe of Japan, its key regional rival, for clues on how the president-elect, who has never held public office, is likely to conduct foreign policy, they said.

South Korea and the United States have agreed to deploy a Terminal High Altitude Area Defense (THAAD) anti-missile system to counter missile threats from North Korea. It is expected to be in place within eight to 10 months, the commander of U.S. forces in South Korea said earlier this month.