Taiwan started its annual, eight-day Han Kuang Exercise on Monday, a war-game to simulate resisting all-out aggression by China, with this year’s centerpiece being anti-airborne operations at Taichung’s Ching Chuan Kang Air Base.

Taiwanese troops wearing red uniforms will mock the tactics likely to be used by the People’s Liberation Army in military offensives against the island, while a group in blue will put up resistance to intercept and delay the invading “foe.”

The drill will consist of joint air-sea combat operations and amphibious warfare in the north and south, as well as joint anti-airborne combat operations in the central regions, said Taiwan’s defense ministry.

The focus of the first two days will be a naval blockage of waterways and ports along the west coast facing China, with the emergent transfer of fighters to unground hangars on the east coast to prepare for a protracted war. Anti-landing and anti-airborne defense combat drills will be held on day three and four.

The joint anti-airborne operations in central Taiwan would be a key part for the military to test its capability to fend off PLA paratroops in a blitz targeting the Taichung air base, home to a number of surface-to-air missile silos that guard the island’s airspace.

Live-fire exercises over the air and sea are to be held off the east coast, in Pingtung and Taitung counties, due to the sensitivity of conducting live-fire drills in the strait facing China to avoid stoking tensions.

However, reports started to emerge on Monday afternoon that two pilots steering an F-16 supersonic multi-role fighter from the red group of the drill had gone missing, with their last known location above the northeastern port city of Keelung. Wreckage believed to be from the fighter was found later in a neighboring mountainous region, but the whereabouts of the two airmen are still unknown.

Taiwanese President Tsai Ing-wen was scheduled to head to Taichung on May 7 to inspect the drill.