By Yimou Lee TAIPEI (Reuters) -Taiwan launches its largest ever military drills on Wednesday, starting with simulated attacks on its command systems and infrastructure ahead of a Chinese invasion, senior defence officials said. The early stages of the annual Han Kuang exercises will focus on testing how Taiwan's military can decentralise command in the event of a crippling communications attack. Over the next 10 days, the drills will expand to assess Taiwan's combat readiness against a full-scale attempt to seize the island. "We are learning from the situation in Ukraine in recent years and realistically thinking about what Taiwan might face ... in real combat," said one senior defence official, highlighting the need to protect command and communication systems. "Commanders have to think what issues their troops might face and they need to pass them down to their subordinates," the official said, speaking on condition of anonymity due to the sensitivity of the operation. Cyber attacks and misinformation campaigns are seen by Taiwan as high-intensity "grey zone" actions that are likely to precede a broader Chinese assault. The annual Han Kuang exercises will this year mobilise the largest number of reservists, some 22,000, and for the first time feature New High Mobility Artillery Rocket Systems, or HIMARS, made by Lockheed Martin, along with Taiwan-developed Sky Sword surface-to-air missiles. Some 300 reserve troops were seen moving into classrooms of a Taipei junior school emptied for summer holidays, cleaning rifles and receiving mortar instruction. China views democratically governed Taiwan as its own and has intensified military pressure around the island over the last five years, including a string of war games and daily patrols. Beijing has never renounced the use of force to bring the island under its control, and any attack on Taiwan could ignite a broader regional war. Taiwanese defence officials said they believed that the Chinese military would be closely monitoring the drills. By 6am Taiwan had detected 31 Chinese aircraft sorties and seven naval ships, the defence ministry said in a statement. Some 24 of the aircraft crossed the median line, the unofficial barrier between the two sides. China's Ministry of Commerce added eight Taiwan firms to its export control list, banning exports of dual use products, the state news agency Xinhua reported on Wednesday. The list includes the Aerospace Industrial Development Corporation (AIDC). As they evolve, the drills will feature 24-hour operations army, naval and air operations to defend Taiwan coasts. Civil defence elements will also be tested, including the creation of emergency supply stations as well as the use of Taiwan's recently-expanded air-raid shelters. China's defence ministry said on Tuesday that Taiwan's Han Kuang military exercises were "nothing but a bluff". "No matter what weapons are used, Taiwan can't resist the People's Liberation Army's sharp sword against independence," ministry spokesperson Jiang Bin was quoted as saying by state broadcaster CCTV. The Taiwanese senior defence official said they wanted to show China that they faced an unpredictable foe and that any invasion scenario was growing more complex, while showing the international community that Taiwan was determined to defend itself. Regional military attaches and analysts say the drills are being closely watched, both for China's response and to gauge improvements in Taiwanese resilience. Taiwan's President Lai Ching-te and his government strongly object to China's sovereignty claims, saying it is up to the island's people to decide their future. (Reporting by Yimou Lee, Ann Wang, Greg Torode and Faith Hung in Taipei; Writing by Greg Torode; Editing by Michael Perry)