Two F-22 stealth fighter jets have joined the ongoing South Korea-U.S. annual military drills here, the U.S. Forces Korea said Monday, in the latest show of force against North Korea.

The radar-evading aircraft, touted for its air-superiority capabilities, arrived at the Osan U.S. Air Base in Pyeongtaek, Gyeonggi Province, on Sunday after departing from the Kadena Air Base in Okinawa, Japan ― the regional hub of America’s airpower.

The mobilization of the F-22 came after Washington sent a series of strategic military assets here such as the B-52 aircraft, B-2 stealth bombers and the nuclear-powered Cheyenne submarine for the drills that end on April 30.

Pyongyang has berated Washington and Seoul for “preparing for a nuclear war of incursion,” threatening to strike key U.S. bases in South Korea, Japan, Guam, Hawaii and its mainland, as well as South Korean units.

“It is important to be very clear about the decision to send American stealth bombers to the Asian region: this was not a U.S. decision, but made by the Combined Forces Command in Korea,” Balbina Hwang, professor at Georgetown University and former State Department advisor, told The Korea Herald.

“This is a very important point because it shows the joint resolve of the U.S.-ROK alliance to deter North Korean provocations and aggression.”

Tension on the peninsula has been escalating with the communist state making a series of saber-rattling moves to protest the allies’ regular drills including the Key Resolve command post exercise and additional U.N. sanctions for its missile and nuclear tests.

Pyongyang said Saturday the Korean Peninsula had entered a “state of war.” It also threatened to shut down the joint inter-Korean industrial complex in its border city of Gaeseong should its “dignity” be undermined.

It has also said it would scrap the armistice agreement and inter-Korean non-aggression pacts. Experts said North Korean leader Kim Jong-un appeared to be seeking to strengthen national unity by capitalizing on rising military tension on the peninsula, and raise the stakes in future negotiations with the U.S.

Seoul officials said by mobilizing the allied intelligence, reconnaissance assets, they were keeping close tabs on North Korean movements, stressing any provocation would be met with “thorough retaliation.”

Manufactured by U.S. defense firms Lockheed Martin and Boeing, the F-22 is a single-seat, twin-engine fifth-generation fighter with capabilities for air-to-air attacks and electronic warfare.

It entered the U.S. Air Force in December 2005. Since then, the F-22 has been a central component of U.S. airpower, and countries unfriendly to the U.S. such as Iran protest its deployment in any adjacent areas.

Due to the F-22 production program, which was criticized for being too costly and protracted, the U.S. stopped short of fulfilling its initial plan to produce some 700 F-22s. A total of 187 units have been produced so far.

Instead, the U.S., along with eight partner nations, has sought to develop cheaper, more versatile F-35 fighter jets. But the F-35 program has also come under fire for the recent discovery of defects, rising costs and delays in development.

By Song Sang-ho (sshluck@heraldcorp.com)