Pentagon officials are sending America's newest strike fighter to South Korea, where they will participate in war games and strengthen the U.S. military's capabilities at a time of historic tensions with North Korea.

"This is the first time we have operated the F-35B in the Republic of Korea," Pentagon spokesman Navy Capt. Jeff Davis told reporters Monday.

That announcement came just as North Korea is pursuing an aggressive schedule of nuclear weapons program tests. The regime reportedly tested a ballistic missile engine on Friday, including technology that "could possibly be used in an eventual intercontinental ballistic missile," according to CNN.

State-run media, meanwhile, has issued a series of bulletins threatening preemptive strikes on U.S. forces in the region.

The F-35, long a controversial fighter jet because of early performance struggles and a price tag that made it the most expensive weapons system in U.S. history, now impresses top military brass as the most advanced air-to-ground fighter available to U.S. allies. "We're doing fantastic," Air Force Gen. "Hawk" Carlisle told reporters in February. "We are going to get that airplane out on the road."

Defense Secretary Jim Mattis is trying to increase the U.S. ability to deter a North Korean attack, while Secretary of State Rex Tillerson makes a diplomatic push with China and regional allies to find a new way to curb the regime's weapons program.

"It goes without saying we are committed to defending the Republic of Korea and Japan against any North Korean aggression," Davis said.