The U.S. military sent a B-1B strategic bomber from Guam over the Korean Peninsula on Wednesday for a massive joint exercise with the South Korean Air Force this week, the U.S. Pacific Air Forces said amid heightened tensions with nuclear-armed North Korea.

The Pacific Air Forces said the B-1B took off from Andersen Air Force Base on Guam, meeting two Air Self-Defense Force F-15 fighters for bilateral drills in airspace near the Kyushu region before heading to the Korean Peninsula.

There, “the bomber participated in an air power demonstration during the ninth iteration of the annual Vigilant Ace exercise,” the U.S. Pacific Air Forces said. It was joined by a total of six of the United States’ most advanced stealth aircraft as well as South Korean fighter jets.

As part of the exercise, the aircraft conducted simulated bombing drills in “a show of the allies’ ability and resolve to retaliate against North Korea’s provocations,” South Korea’s Yonhap news agency quoted unidentified defense authorities there as saying.

Several U.S. F-35 stealth fighters, F-16s and South Korean F-15Ks and KF-16s took part in the exercise at the Pilsung Firing Range in Gangwon Province, Yonhap said, citing the South’s Joint Chiefs of Staff.

The Vigilant Ace exercise, which kicked off Monday and will run through Friday, involves more than 200 aircraft, including six U.S. F-22 and 18 F-35 stealth fighters. It comes on the heels of North Korea’s test last week of its most powerful long-range missile, which experts say puts all of the United States within striking distance.

The North has warned that the exercise could push the Korean Peninsula to “the brink of nuclear war.”

In a commentary Tuesday, the North’s official Rodong Sinmun called the exercise “a trite method employed by aggressors to mount a sudden preemptive attack while pretending to conduct war drills.”

Overflights of the Korean Peninsula by heavy bombers such as the B-1B have incensed Pyongyang. The North views the flights by what it calls “the air pirates of Guam” as a rehearsal for striking its leadership and has routinely lambasted them as “nuclear bomb-dropping drills.”

The U.S. Air Force last flew B-1Bs over the peninsula in early November, just days ahead of Donald Trump’s inaugural visit to Asia as U.S. president.

Also in November, the U.S. Pacific Air Forces confirmed to The Japan Times that it had flown two B-52 strategic bombers capable of carrying nuclear weapons for a rare joint mission with the ASDF in the skies near North Korea in August.