Two US B-1B strategic bombers flew over South Korea on Saturday as part of their participation in the Seoul air show.

The long-range, multi-mission supersonic bombers flew low over Seoul Air Base for eight minutes as part of the air show, formally called the Seoul International Aerospace and Defense Exhibition 2017.

The first one appeared in the skies over the air base, escorted by two South Korean F-15K fighter jets, and flew as low as just 450-500 meters above the ground before exiting to the west. Then came the second that flew even lower, just 150-200 meters above the site.

"Their altitudes were so low that they were seen well from the stands, and not only the roar, but even a little vibration was also felt that spectators gaped at them," a defense ministry official said.

The bombers took off from Guam's Anderson Air Base earlier in the day before entering the skies of South Korea. Sources said the bombers and two South Korean F-15K jets conducted simulated air-to-surface missile firing drills.

The flyover comes 11 days after two B-1B bombers carried out surprise nighttime exercises over the waters off South Korea's east and west coasts in a show of force against North Korea.

Officials said the US is expected to fly B-1B bombers over South Korea every two to three weeks to help deter the communist nation. (Yonhap)