Exclusive: Flight mission near North Korean border exhibits US motto there: 'Fight tonight'

 ABC News Martha Raddatz flies in a F-16 ten miles from the North Korea border with the 51st Fighter Wing as it prepares at all times to "fight tonight."PlayABCNews.com
WATCH Fly along with the 51st Fighter Wing near the North Korea border

The motto of the more than 28,000 U.S. forces stationed in South Korea -- "fight tonight" -- emphasizes their readiness to mount a defense against a North Korean threat at any time.

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ABC News' Chief Global Affairs Correspondent Martha Raddatz saw how seriously U.S. forces take that saying while accompanying service members on a F-16 flight along the North Korean border this week.

Raddatz participated in a training operation with the 36th Fighter Squadron, a part of the 51st Fighter Wing, which simulated a North Korean invasion into South Korea.

The F-16 crew practiced giving backup to ground troops in need of close air support by conducting fake strikes on air defenses and tanks from a restricted air space known as P-518, which is just 10 miles from the North Korean border and as close as U.S. pilots can get to the regime's territory.

While no bombs were dropped during the simulation, a real Army unit was on the ground calling in the fake airstrikes.

The purpose of the restricted air space is to control aviation operations and prevent “inadvertent overflight of non-friendly borders,” according to U.S. Forces Korea.

"It must be strange, we're not really in a war zone, but it could happen at any time," Raddatz said to the pilot, call sign "True" Daniels, during the flight mission.

"I'll tell you, it definitely gives you a real purpose for waking up in the morning," Daniels responded, adding, "And that's our mission here, is to be ready to fight at a moment's notice."

The 36th Fighter Squadron flies approximately 170 sorties, or flight missions, from Osan Air Base in South Korea every week.