5 questions to ask about China's seizure of US underwater drone

The oceanographic survey ship, USNS Bowditch, which deployed an underwater drone seized by a Chinese Navy warship in international waters in the South China Sea.

HONG KONG (BLOOMBERG) - A Chinese naval vessel seized a US underwater drone operating off the coast of the Philippines, sparking a protest from the Pentagon. 1. HAS ANYTHING LIKE THIS HAPPENED BEFORE?

While confrontations between US and Chinese military ships or planes occur on occasion, this is the first time China has seized an American underwater drone. The last major incident between the nations in the South China Sea happened in 2013, when a Chinese vessel nearly collided with the Cowpens, an American missile-carrying cruiser. Four years earlier, Chinese ships had reportedly harassed the US Navy vessel Impeccable, leading to American protests. In 2001, shortly after former President George W. Bush took office, a Chinese jet collided with a US spy plane operating in the South China Sea, which made an emergency landing on Hainan Island. China eventually released the crew and the plane after the US expressed regret for the death of a Chinese pilot and for entering Chinese airspace without verbal clearance.

2. WHAT IS THE ROOT OF THE PROBLEM?

China and the US have different interpretations of what military activities can take place near a nation's shores. China has long opposed US military patrols and surveillance within its exclusive economic zone, an area stretching 200 nautical miles from land. The US views anything beyond 12 nautical miles as international waters in which military activities can take place. In recent years, the US and China have joined agreements that aim to reduce the chance of conflict during unplanned encounters at sea. China has also sought to avoid moves that raise tensions as it builds up military installations on islands it claims in disputed areas of the South China Sea.

3. WHAT'S SURPRISING ABOUT THIS INCIDENT?

The location of the seizure - about 50 nautical miles away from the Philippines - is particularly interesting. Not only is outside of China's exclusive economic zone, but also beyond its more expansive nine-dash line encompassing about 80 per cent of the South China Sea, according to Greg Poling of the Asia Maritime Transparency Initiative.

4. WHAT COULD EXPLAIN THE SEIZURE?

Many theories are floating around. According to Zhang Baohui, director of the Centre for Asian Pacific Studies at Lingnan University in Hong Kong, one possibility is that the American drone was conducting surveillance against a Chinese nuclear submarine, and China felt the need to deny the US vital military secrets. Alternatively it may have been a response to Pacific Command chief Harry Harris's comments last week that the US would confront any Chinese attempts to control the South China Sea. Less likely, it may be due to President-elect Donald Trump's recent questioning of US policy towards Taiwan or a move by an overly assertive military commander. "Chinese naval and coastguard vessels operate within the bounds of guidelines that are centrally dictated by officials in Beijing," said Ashley Townshend, research fellow at the United States studies centre at the University of Sydney. "Any changes to established patterns of maritime behaviour, like Thursday's drone incident, would normally need to be pre-approved - particularly if the new actions are likely to be provocative."

5. WHERE ARE THINGS LIKELY TO GO FROM HERE?

Early indications appear that China will return the drone. The Global Times, a state-run newspaper affiliated with the Communist Party, cited an unnamed Chinese official saying it seized the unidentified device due to concerns over navigation safety. China had received the US request to return the device, and the matter should be resolved smoothly, the report said.