South Korea and the US on Friday staged another military air exercise over the west coast of South Korea by mobilizing their stealth fighters, just two days after US strategic bombers flew to the Korean Peninsula for combined aerial drills.

The air combat exercise involved F-22 and F-35B advanced stealth fighters and F-16CM fighting aircraft of the US Air Force and South Korean Air Force’s F-35A stealth fighter jets, according to South Korea’s Air Force.

“The combined exercise aimed to enhance the capabilities of the South Korean and US air forces to carry out combined operations and interoperability as well as demonstrated the US capabilities and its unwavering resolve to carry out its commitment of defense to South Korea,” the Air Force said in a statement.

South Korea’s Air Force said it would continue to bolster combined training exercises with the US Air Force to “reinforce their readiness posture and capabilities to counter North Korean nuclear and missile threats while maintaining ironclad combined defense posture.”

The series of aerial drills came after the South Korean and US defense chiefs on Tuesday agreed to step up combined field training exercises and the deployment of US strategic assets and advanced fifth-generation fighter jets, including F-22s and F-35s. The agreements elicited backlash from North Korea, which warned the US of facing the “toughest” response should the allies put plans into action in a statement on Thursday.