Why is the US reluctant to give South Korea wartime control of its troops?

South Korea wants to take back wartime command of its troops from the United States within the next two years, but analysts say Washington is refusing to commit to a date to keep a hold on a military it sees as vital to countering China.

The dispute is over wartime operational control, known as OPCON, which the US has held since shortly after the outbreak of the Korean war in 1950.

If fighting were to break out again under the current arrangements, designated South Korean units would be assigned to the Combined Forces Command, a joint warfighting headquarters led by US General Xavier Brunson. The exact units involved are classified, but are thought to include all frontline army units and large parts of the air force and navy.