BTS perform onstage during the 64th Annual Grammy Awards.

K-pop boy band BTS reunited on Saturday for a concert in Busan in support of South Korea’s bid to host the World Expo 2030 in the southern port city.

The free concert – titled “BTS Yet To Come in Busan” – drew an audience of about 52,000 people to a stadium, according to the Yonhap News Agency.

A total of 100,000 were expected to visit the stadium and other areas, according to Busan Metropolitan City authorities, with some fans watching the event live on large screens set up at several places around Busan.

The concert followed the seven-member band’s announcement of a break in June from group musical activities to pursue solo projects, raising questions about the band’s future.

With BTS’ oldest member, Jin, who is turning 30 next year, facing South Korea’s mandatory military service, the country’s defense minister said in August that BTS might still be able to perform overseas while serving in the military.

BTS fans queue outside Busan Asiada stadium to attend the band's free concert in South Korea on October 15, 2022.

Under a 2019 revision of the law, globally recognized K-pop stars were allowed to put off their service until 30. Military service is hugely controversial in South Korea where all able-bodied men aged between 18 and 28 must fulfill their duties as part of efforts to defend against nuclear-armed North Korea.

“If the seven BTS members feel the same way and if you guys have faith in us, we will overcome whatever happens to us in the future and we will perform with you guys and make music. Please have faith in us,” BTS leader RM told fans during the concert, without elaborating further.

Four countries – South Korea, Italy, Ukraine and Saudi Arabia – have submitted competing candidatures to organize World Expo 2030, according to the expo organizing body Bureau International des Expositions (BIE). The host country of the World Expo 2030 is expected to be elected next year.

In July, BTS were made official ambassadors for the World Expo 2030 in Busan, over 300 km (190 miles) southeast of capital Seoul.

BTS made their debut in June 2013 and became a worldwide sensation with its upbeat hits and social campaigns aimed at empowering young people.

Last year, BTS became the first Asian band to win artist of the year at the American Music Awards. The group met US President Joe Biden at the White House in May to discuss hate crimes targeting Asians.