The taking of the unmanned underwater vehicle in international waters near the Philippines triggered a US diplomatic protest and speculation about whether it would strengthen US President-elect Donald Trump's hand as he seeks a tougher line with China or whether China was testing him.
The Chinese navy returned the drone on Tuesday after what it said were friendly talks with the United States.
Asked whether China dismantled the drone to inspect it, or whether the navy deliberately targeted the drone or if it was picked up by mistake, foreign ministry spokeswoman Hua Chunying said she had no details about the incident other than those provided by the defence ministry.
"There is a bit of over-reading, or a bit thinking about it too much: 'was it a misjudgement or orders from higher up'?" Hua told a daily news briefing, referring to a reporter's question.
The seizure has added to US concern about China's growing military presence and aggressive posture in the disputed South China Sea, including its militarisation of maritime outposts.
China is deeply suspicious of any US military activity in the resource-rich South China Sea, with state media and experts saying the use of the drone was likely part of US surveillance efforts in the disputed waterway.
(Reporting by Ben Blanchard; Editing by Robert Birsel)
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