cheerleader

noun

Etymology: From cheer + leader.

1. A person, usually a young, attractive female, who encourages applause and cheers at a sports event, and wearing a specially-designed uniform in the official colors of the team he/she cheers for.
2. A person who rallies support for any cause.

   “Given these sentiments, it is unsurprising that ultranationalists have been the main cheerleaders of closer Russia-North Korea relations.”