Story highlights

NEW: War games to include attacks on mock North Korean missile sites, South Korean official says

North Korean, US officials both say dangers of war growing

CNN  — 

US F-22 fighter jets roared into the sky over South Korea on Monday to start air combat exercises that North Korea says are pushing the peninsula to the brink of nuclear war.

A US 7th Air Force official said the top-of-the-line F-22s are being joined by Air Force and Marine Corps F-35s in the largest concentration of fifth-generation fighter jets ever in South Korea.

A senior South Korean Air Force official told CNN on Monday that the war games will include attacks against a mock North Korean missile launch site with mock North Korean radars.

Experts say the stealthy F-22s and F-35s would be key to any such actual attack as they are invisible to North Korean radars.

The fighter jets are among 230 US and South Korean aircraft – supported by 12,000 troops – participating in the annual Vigilant Ace 18 air combat drills, which are scheduled to end Friday.

North Korea state media said Monday that “ceaseless large-scale war games” by the US and South Korea are “creating a situation that a nuclear war may break out any moment.”

Over the weekend, official sources from both North Korea and the US said the chances of war are growing.