What is Foal Eagle?

Foal Eagle, the two-month long military exercise underway in South Korea with American forces, is one of the largest and longest war games in the world. The annual event is a chance for U.S. and South Korean forces to practice responding to an invasion — and to show some might in the process.

This year, however, Foal Eagle has drawn considerably more attention due to persistent threats of nuclear war from North Korean leaders, unhappy with the show of force at their doorstep. Here’s what they’re worried about:

The bilateral exercise, which the Pentagon says is purely to train for a defensive operation, is a combination several smaller individual air, land, and sea elements, including special operations forces. This year’s Foal Eagle started around March 1 and runs through April 30. An estimated 10,000 U.S. troops are involved directly, with additional service members supporting the war game from afar.

In early March, the U.S. and South Korea practiced coordinating and deploying air forces, according to the U.S. 7th Air Force. Those aircraft included: “F-16s from the 8th Fighter Wing, Kunsan; A-10s and F-16S from the 51st Fighter Wing, Osan Air Base; E-3s from the 18th Wing, Kadena Air Base; numerous [South Korean Air Force] aircraft; and accompanying support personnel during the week-long exercise.”

But far more press attention has followed the F-22 Raptors, B-2 stealth bombers, and B-52s also involved in the exercises last month. On March 28, the U.S. announced two B-2 stealth bombers had joined the exercise. The B-2s, which are capable of carrying nuclear weapons, practiced a bombing run, dropping inert ammunition on Jik Do Range, which is on an island off the west coast of South Korea. The bat-winged bombers also flew a low-level pass above Osan Air Base, the major U.S. Air Force base in South Korea just south of Seoul, showing off its mere presence.

“This mission by two B-2 Spirit bombers assigned to 509th Bomb Wing, which demonstrates the United States’ ability to conduct long range, precision strikes quickly and at will, involved flying more than 6,500 miles to the Korean Peninsula, dropping inert munitions on the Jik Do Range, and returning to the continental U.S. in a single, continuous mission,” boasted U.S. Pacific Command, in a blustery statement of its own.

The F-22s were flown in but did not perform any mock strike operations. In case of war with North Korea, F-22s could be among the first U.S. aircraft sent to knock out air defenses, allegedly without being detected, or to escort bombers. But, for the recent show of force, the U.S. Air Force simply put the advanced stealth fighters on “static display,” meaning they were parked while senior South Korean military leaders — very publicly — reviewed America’s premier fighter up close and personal. They also received an orientation and “familiarization training,” said Col. Kathy Wilkinson, a Pentagon spokeswoman. That training “includes pilots talking about how they fly to planners talking about integrating that asset into combined arms operations.”

At sea, by the second week of March, four Arleigh Burke-class guided-missile destroyers — the USS Lassen (DDG 82), USS Fitzgerald (DDG 62), USS John S. McCain (DDG 56), and USS McCampbell (DDG 85) —  had arrived in South Korea. The ships are part of the Japan-based Destroyer Squadron (DESRON) 15, and conduced naval drills alongside South Korean vessels.

The war games are not all business. One purpose for holding multinational exercises is for U.S. troops to meet their foreign counterparts. “While in port, DESRON 15 ships and ROK Navy sailors participated in sports tournaments, local community service projects, ship tours and conducted military-to-military engagements, including the liaison exchange of ROK and U.S. Navy sailors who embarked on board their counterpart’s ship to participate in the exercise,” an internal Navy news report noted.

But this week, the fun and games ended. A fifth ship of the same class, the USS Decatur, was on its way back into San Diego when the Navy turned her around and ordered her to remain on alert in the Western Pacific, due to the North Korean threat. The Decatur joined the McCain, also being kept in the region, to provide missile defense capability via on-board Aegis systems.

“They have arrived at predetermined positions in the western Pacific, where they will be poised to respond to any missile threats to our allies or our territory,” said Pentagon press secretary George Little, on Tuesday. Little said the ships were not patrolling “off the North Korean coast,” as had been reported.

Underwater, the U.S. conducted naval exercises with the USS Cheyenne (SSN 773), a Los Angeles-class fast attack submarine, which also made port calls. It’s yet another way to show U.S. might up close and personal. The Cheyenne is not equipped with nuclear weapons, but has Tomahawk cruise missiles, Harpoon anti-ship missiles, and Mark-48 torpedoes, giving it the ability to strike targets near and far, on land and sea. Tomahawk missiles were key in taking out air defenses in Libya in 2011. The boat is in the middle of a six-month deployment that began in December.

In mid-March, the Eighth Army also held exercise Key Resolve, involving 10,000 Korean and 3,000 U.S. forces, which let commanders practice controlling allied land forces in a computer simulation.