The US government on Friday confirmed that it conducted military exercises with Japan, but declined to comment on the scenario of the drills, which a Financial Times report said involved combating China to defend Taiwan.
US Department of Defense spokesman John Kirby made the remarks at a news conference in response to a report on Thursday by the Financial Times.
Citing two unnamed US defense officials, the report said that the US and Japan have conducted secret war games around the Diaoyutai Islands (釣魚台), known as the Senkakus in Japan, which were billed as disaster relief drills, but were intended as joint military exercises to fight China in a dispute over Taiwan.
Taiwan, the US and Japan have shared military aircraft identification codes since 2017, it added.
Japan had requested that the US share with it plans to defend Taiwan, but the US Department of Defense instead opted to enhance military cooperation with Tokyo in phases, it said.
“The eventual goal was for the allies to create an integrated war plan for Taiwan,” one official was quoted as saying.
Taiwanese experts said that news of the government sharing military aircraft identification codes with the US and Japan was a positive national security development.
Su Tzu-yun (蘇紫雲), an associate research fellow at the Institute of National Security and Defense Research, said that code-sharing is a necessary step before Taiwan, the US and Japan can conduct joint operations concerning the Taiwan Strait.
The codes are used by identification friend or foe (IFF) systems to identify aircraft, which increases engagement speed, he said.
“There were reports that Taiwan and the US are sharing the codes, so it makes sense that there is a trilateral arrangement,” he added.
The US is increasingly making public the advisers and activities of its security cooperation brigade in Taiwan, and broadening its exchanges in tactics, operations and strategy with the nation’s forces, he said.
Trilateral military cooperation must be allowed to develop at its own pace, and the process should not be rushed, he added.
The three countries had an understanding to share IFF codes, which is an important import breakthrough in relations, a source familiar with the matter said.
Sharing the codes means that Taiwan does not have to treat US military airplanes as unidentified aircraft in the Taipei Flight Information Region, which boosts flight safety and military efficiency, and conserves wear and tear on fighter jets, they said.
Erich Shih (施孝瑋), editor-in-chief of the Military and Aviation News Web site, said the arrangement would allow Taiwan to identify friendly US and Japanese aircraft.
If the US and Japanese aircraft were unknown, the military would have to intercept them with fighters or other air defense assets, he said.
The Air Force Command Headquarters said it had no knowledge of the article.
Additional reporting by CNA