Seoul, Jul 14 (IANS): South Korea and the United States have been conducting their first combined air drills here involving their respective F-35A stealth fighters, Seoul officials said Thursday, in an apparent show of force against North Korea's evolving military threats.

The four-day drills kicked off Monday amid lingering concerns that Pyongyang could ratchet up tensions by conducting what would be its seventh nuclear test or other provocative acts, Yonhap news agency reported.

The allies have mobilised some 30 aircraft, including South Korea's F-35A, F-15K, KF-16 and FA-50 jets, and US assets, like F-16 jets. Six US F-35As arrived here last week to join the drills in the first public deployment of America's stealth warplanes here since late 2017.

"The drills have been arranged to improve combined operational capabilities of the two countries through real-life training and strengthen the interoperability of the fifth-generation F-35As run by the countries," the Air Force said in a press release.

The drills marked the first combined training involving the allies' respective F-35As since South Korea completed the deployment of 40 F-35As in January.

The training entailed various maneuvers, including defensive counter-air operations and emergency air interdiction.

Lt. Col. Ryan Worrell, a US F-35A pilot, said the primary objective with this week's training is to safely execute tactics between US and South Korean F-35As to show "our ironclad alliance."

The last public deployment of the US' fifth-generation fighters to Korea came in December 2017, when the allies staged their then regular Vigilant Ace training.

The latest F-35 dispatch followed an agreement from the May summit between President Yoon Suk-yeol and his US counterpart, Joe Biden, on deploying America's strategic military assets "in a timely and coordinated manner as necessary."