The Chinese and American militaries have yet to work out rules about the use of drones that both are increasingly deploying to monitor the disputed South China Sea. Yet US president-elect Donald Trump was quick to accuse Beijing through his Twitter account of stealing an unmanned underwater vehicle that a navy ship had pulled aboard. China steals United States Navy research drone in international waters - rips it out of water and takes it to China in unprecedented act. — Donald J. Trump (@realDonaldTrump) December 17, 2016 <!--//--><![CDATA[// ><!--\n\n\n//--><!]]> The incoming commander-in-chief has much to learn about the job he takes up in a month, but as his controversial use of social media has already shown in remarks about Taiwan , he tends to share his views without regard for the facts or protocol. It is a dangerous game when dealing with sensitive issues. ‘I don’t know why we have to be bound by a one-China policy’: Trump questions decades-long stance Outgoing leader Barack Obama is only too aware of circumstances, which is why a day after the drone was taken he stressed the need for following established principles. He advised Trump to carefully consider his actions and any new policies so as not to inflame tensions. Rightly he pointed out the significance of the principle of one China and that on issues like Taiwan, it is non-negotiable. The incoming president has worryingly suggested otherwise. Sovereignty claims in the South China Sea are a different matter, but no less sensitive. Trump, although an establishment outsider, should know from his business experience how misplaced words or actions can cause harm. Several times over the past 15 years, Sino-US relations were put into crisis in the region through military carelessness, most seriously in 2001 when a US surveillance plane and a Chinese fighter jet collided near Hainan. The incident involving the drone was nothing as momentous; while its purpose is disputed as is the location in which it was taken, there has been no loss of life and after low-key negotiations, Beijing on Tuesday returned it to the US navy. China hands back US drone but regional tensions expected to linger Trump likes to shoot from the lip, but it is no way to conduct foreign policy. Tensions can easily escalate, which is why long-established approaches have to be faithfully followed. Where there are grey areas, such as with the use of drones, diplomacy and negotiations are the only way forward.