The U.S. and South Korean militaries have suspended another joint exercise this year as diplomatic efforts continue with North Korea, the Defense Department said Oct. 19.

Defense Secretary James Mattis and Minister of National Defense Jeong Kyeong-doo suspended Exercise Vigilant Ace, an annual large-scale exercise to enhance interoperability between the U.S. and ROK forces, “to give the diplomatic process every opportunity to continue,” said chief Pentagon spokeswoman Dana White in an emailed statement. Japanese Minister of Defense Takeshi Iwaya was consulted on the matter, she added.

Marines from South Korea, Thailand and the United States set up their assault amphibious vehicles for a group photo at Hat Yao Beach, Rayong province, Thailand, after coming ashore from the USS Bonhomme Richard (LHD 6) Feb. 17, 2018. The Marines participated in an amphibious assault in support of Exercise Cobra Gold 2018. Cobra Gold is one of the largest exercises in the Indo-Pacific region and improves the capabilities of participating nations in the event of a regional contingency or natural disaster. (U.S. Air Force photo by Tech. Sgt. Michael Lee Brown)
Marines from South Korea, Thailand and the United States set up their assault amphibious vehicles for a group photo at Hat Yao Beach, Rayong province, Thailand, after coming ashore from the USS Bonhomme Richard (LHD 6) Feb. 17, 2018. The Marines participated in an amphibious assault in support of Exercise Cobra Gold 2018. Cobra Gold is one of the largest exercises in the Indo-Pacific region and improves the capabilities of participating nations in the event of a regional contingency or natural disaster. (U.S. Air Force photo by Tech. Sgt. Michael Lee Brown)

This exercise is not on the same level as the “Tier 1” Ulchi Freedom Guardian exercise that was suspended in June in an effort to give Secretary of State Mike Pompeo and other diplomats more opportunities to negotiate with North Korean leader Kim Jong-Un, a Pentagon spokesman told reporters Friday.

Tier 1 exercises bring all of the services together and involve more high-level situations, he noted. Exercise Vigilant Ace involves air operations. Training and exercises continue with South Korean counterparts on a smaller scale, he added. The two next Tier-1 exercises, Foal Eagle and Key Resolve, are currently still scheduled for spring 2019, the Pentagon said.

The previous Vigilant Ace exercise took place Dec. 4-8, 2017 at Osan Air Force Base, South Korea. The two countries combined their forces with approximately 12,000 troops and 230 aircraft participating, according a 2017 U.S. Indo-Pacific Command release. The U.S. and South Korean militaries have been working together in this particular exercise for the past nine years, which until 2017 was known as Beverly Bulldog.

The Pentagon’s new top general in South Korea, Army Gen. Robert Abrams, told lawmakers that the troops on the Korean peninsula had seen a “degradation to the readiness … of the combined forces” during his nomination hearing for U.S. Forces-Korea commander before the Senate Armed Services Committee (SASC) Sept. 25 (Defense Daily).

“That’s a key exercise to maintain continuity and to continue to practice our interoperability, and so there was a slight degradation,” he said.