The firing of US Defence Secretary Mark Esper has triggered worries in Beijing about the increasing risk of accidental conflict as well as the possibility of more hardline action by the Pentagon against Beijing, according to military analysts. The departure of Esper has long been expected – he had previously contradicted US President Donald Trump. But Beijing remains worried that tensions may spike now because the US official was seen as willing to communicate with Beijing. The appointment of Christopher Miller as acting defence secretary is also a concern. “Miller has a strong special forces background. He joined the special forces and commanded it and specialises in surprise attacks and adventure operations,” said Beijing-based military expert Zhou Chenming. Zhou said China was concerned about “possible military adventures” because the US had already stepped up its security ties with Taiwan and other claimants of the disputed South China Sea , moves that dismayed Beijing. Esper was “stable” and could be engaged, Zhou said, adding that Miller’s background in special forces had led to speculation he would be more determined to take drastic action against China. Late last month, just a few days before the US presidential election , Chinese and American defence officials agreed to hasten talks during a potential crisis, a show of willingness to prevent all-out conflict. During that first meeting of the Crisis Communications Working Group , the Pentagon denied rumours that the Trump administration might launch an attack against China’s artificial islands in the South China Sea . On Monday, US marines started a four-week training programme with their Taiwanese counterparts, which the Taiwanese Navy Command described as a “routine Taiwan-US military exchange and cooperation training to improve the combat capabilities of Taiwanese troops”. The US marines spent two weeks in quarantine before their joint training drills started, indicating that the decision to send them to Taiwan was made well before the US election and before Trump fired Esper. A source close to the People’s Liberation Army said Beijing had seen the joint training as “a move to challenge its bottom line”, and that there was the risk of conflict in the South China Sea. “Taiwan’s [independence-leaning] Tsai Ing-wen administration is taking a salami-slicing tactic. It’s very dangerous when the American military also encourages Tsai to take a further move,” the source said. Taiwan seeks US help to boost its defences as Beijing ramps up pressure “The PLA leadership wonders if someone in the American military is going to take a risk and cause accidental conflicts with the Chinese military, especially in the South China Sea, following Esper’s termination.” The US has ramped up its military operations in waters off the East and South China seas, where China has territorial disputes with Japan, Vietnam, Malaysia, the Philippines and other Southeast Asian countries. Beijing has criticised America’s “freedom of navigation” operations and flight surveillance near Chinese coasts and artificial islands, accusing the US of challenging China’s sovereignty and national security. There have been accidental conflicts and near-misses between the US and Chinese militaries in the South China Sea, including one on April 1, 2001 that killed a PLA pilot after his J-8 fighter jet collided with a US EP-3 spy jet. At the same time, the Pentagon has authorised US warship commanders to make a judgment call on whether to open fire when faced with risk. US and China push to modernise ships’ weapons in race for naval dominance Zhou said the American military’s intensive military operation and their rules of engagement had increased the risk of accidental conflicts. Miller, 55, is a graduate of George Washington University and also holds degrees from the Naval War College and the Army War College. He served in the military from 1983 to 2014 and most recently served as deputy assistant secretary of defence for special operations and combating terrorism. He also took part in combat operations in Afghanistan in 2001 and the second Iraq war in 2003, according to his National Counterterrorism Centre official biography. However, Drew Thompson, a former US defence department official with responsibility for managing US relations with mainland China and Taiwan, said he did not foresee a greater risk of accidental conflict between the two militaries before US President-elect Joe Biden is inaugurated on January 20. “I don’t think Miller can do anything significant in the next two months,” he said. “His biggest legacy would be ensuring a smooth transition, serving the national interest in continuity and setting his successors up for success.” Hong Kong-based military commentator Song Zhongping agreed, adding that the Trump administration would pay more attention to domestic issues. “Trump is unhappy for the loss. He is not interested in wasting time on China-US diplomatic issues, letting the US military continue their routine operations and training in the Pacific,” he said.