As of writing, their 'Pt.1' song "Dope" is number 3, 'Pt.2' song "Butterfly" is number 7, and 'Pt.1' song "I NEED U" is number 8.
The K-pop music category on the U.S. iTunes was implemented just last week. This official category was long overdue, as K-pop music has been popular on iTunes for a while now.
When their 'Pt.2' album first came out, it also placed first and second in various countries, including France, Finland, Vietnam and Malaysia.
Congrats to BTS!