Mil Mi-8 helicopters were among aircraft taking part in an exercise staged at the Zhurihe training base in the Inner Mongolia Autonomous Region in August, 2014. The exercise involved Shanghai Cooperation Organization members China, Russia, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan and spokesperson Yang Yujun said the drill progressed smoothly, with troop exercises beginning on Friday. [Photo/Xinhua]

The development forms part of two mutual trust-building mechanisms

Wu Qian, newly appointed Ministry of National Defense spokesman [CHINA DAILY]

China and the United States have signed annexes to two agreements regarding major military operations and naval and air force encounters.

Beijing confirmed the news－which comes amid President Xi Jinping's state visit to the US－on Thursday, saying the annexes had been signed by defense officials from both countries on Sept 18.

Observers said the approval signifies major policy progress and consensus to avoid miscalculation in the Western Pacific at a time when the two militaries are increasingly overlapping there, sometimes triggering tension accidentally.

Wu Qian, newly appointed Ministry of National Defense spokesman, told a scheduled news conference in Beijing the two annexes－"notification of military crisis" and "encounters in the air"－had been signed as part of two mutual trust-building mechanisms between the two countries.

The development marks new progress in building the mechanisms－a reporting system on major military operations and a code of safe conduct on naval and air force encounters, Wu said.

The "encounters in the air" annex clarifies rules, including those to ensure safe flying, exercising fundamental liaison and communication, announcing designated danger zones or warning zones, and coordinating efforts at the scene of emergencies.

The first annex is aimed at regulating mutual notification of a military crisis by using the telephone hotline between the two defense ministries, Wu said.

Zhang Junshe, a senior researcher at the PLA Naval Military Studies Research Institute, said the "encounters in the air" annex will be extremely useful, as it will serve as a set of rules to ensure that aerial encounters by the two militaries over the ocean are guided and regulated.

"Strategic mutual trust between the two militaries will be strengthened, and there will be less chance of incidents or conflicts taking place," Zhang said. "Miscalculations or misunderstandings can be avoided as much as possible."