“Dynamite,” the first single recorded entirely in English by South Korean pop sensation BTS, is a bonafide hit in the U.S. following a successful launch at Top 40 radio coupled with key television appearances, like the MTV Video Music Awards on Aug. 30 and the group’s performance on the “Today Show” this morning (Sept 10).

For fans of the band, such an embrace of BTS in the U.S. was always a question of when, not if. So why now and what is it about the feature-less “Dynamite” that resonates with the Top 40 gatekeepers and their respective audiences? And does its success (more than 11,000 radio spins across all formats since its release on Aug. 28, according to Mediabase, quickly catching up to 2019’s “Make It Right” featuring Lauv with 17,240 plays), along with that of Blackpink and Selena Gomez’s bubbling “Ice Cream” (coming up on 2,000 Top 40 spins), mark K-pop’s broader breakthrough moment?

Much of the magic of “Dynamite,” which was co-written (with Jessica Agombar) and produced by David Stewart for BTS (and packaged by Hallwood Media), comes down to its bop factor — the undeniable hook of the chorus, the bounce of its dance floor-ready groove — but credit is also due to how the voices of the seven members — RM, Jin, Suga, J-Hope, Jimin, V and Jungkook — blend together on the song’s harmonies and stand on their own during solo turns.

For that, BTS fans have vocal producer Jenna Andrews to thank. A former artist herself who was signed to Island Def Jam, and a longtime writer and producer whose credits include Benee’s equally addictive “Supalonely” as well as tracks by Noah Cyrus, Jessie J. Tori Kelly and Little Mix, Andrews worked on “Dynamite” for three weeks and was specifically tasked with shepherding the vocals as they were being recorded remotely from South Korea.

“I have so much admiration for real singers,” Andrews tells Variety. “And I like approaching the vocal performance emotionally because I think the thing that really gets people is conviction and believability. The technical stuff you can do it after. First is getting a singer into a mind-space or finding a melody and the right key where their voice shines the most. When they’re comfortable in their range, they’ll sing it with more confidence.” (Andrews also co-heads Sony/ATV-affiliated TwentySeven Music Publishing and serves as an A&R consultant at RECORDS, home to Cyrus and 24kGoldn, among other acts.)

Andrews’ responsibilities on “Dynamite” included arranging the harmonies, timing and editing for the vocals. For direction, she’d record her own voice as a guide. Using SourceConnect and guiding her engineer on ProTools, Andrews would have direct access to the singer in the vocal booth and also be able to see the artist via video.

“With BTS, I got the lead vocals that they sang and I helped coach them with pronunciation while also trying to keep their quirks so that they’re still authentically BTS,” Andrews explains. “Their voices are really f–ing good. I was, like, ‘Holy sh–!’ They really came with it.”

Some of the vocal parts weren’t easy to perform. J-Hope’s, for example. “The song was really high for him but I think he sounds great,” says Andrews. Jin has also mentioned that recording in English was a challenge but also fun — a sentiment Andrews echoes. “They worked so hard and did everything to really make sure it was top-notch.” Andrews’ favorite part? “The bridge when everything comes together,” she says. “It has that Jackson 5 moment. Everybody came to the table and delivered.”

Asked if BTS has its own secret sauce when it comes to vocal layering, Andrews offers: “The answer is it’s kind of trial and error. It’s like jigsaw puzzle where you have to put it in a bunch of different ways until it fits. We spent a ton of time on it and wanted to make sure it was perfect. Again, it’s not even that much about the technicality; it’s more about that feeling.”

Americans are, indeed, feeling the boom of “Dynamite,” much like Andrews herself reacted when she first heard the song in its incomplete form. “I was, like, ‘Holy s–t, this a huge song,'” she recalls. “It was perfect for them. It’s in a cool style that felt authentic for BTS. And they’re such good dancers that they can really sell the song.”

Beyond North American borders, Andrews, who’s a native Canadian, sees “Dynamite” as a “universal” song. “They’re due for world domination,” she adds. “After this song, s– is going to go wild. … It checks all the boxes. It’s not just a moment. You can like it at 10 years old and at 50.”