Beijing - Chinese state media said Monday US President-elect Donald Trump's diplomatic inexperience could spark a confrontation between the two nations, while one newspaper termed him unfit to lead a superpower.
They were commenting on Trump's response to Beijing's seizure of a US maritime probe in international waters, a move which raised already heightened tensions between the world's two largest military powers.
A Chinese naval vessel "unlawfully" grabbed the unmanned underwater vehicle in the South China Sea around 50 nautical miles northwest of Subic Bay in the Philippines, the Pentagon said Friday.
China said the drone had been snatched since it might pose a safety hazard to other vessels.
It also said it "strongly opposed" US reconnaissance activities and had asked Washington to stop them.
The US said the device was collecting information on water temperatures, salinity and sea clarity.
On Sunday, after Beijing and Washington announced the drone would be returned, Trump tweeted: "We should tell China that we don't want the drone they stole back. - let them keep it!" In a previous tweet, he had called China's move an "unpresidented (sic) act", with the misspelled word going viral - to much ridicule - before he corrected it.
"What is truly amazing about this tweet, was the soon-to-be US president completely misrepresented what had actually happened - that is more dangerous than funny," an editorial in the state-owned China Daily newspaper said.
Trump's behaviour "could easily drive China-US relations into what Obama portrays as 'full-conflict mode'," it added, next to a cartoon that depicted Trump riding a bull into a china shop while US businessmen looked on aghast.
A separate article quoted experts as calling Trump's behaviour "diplomatically inept".
Trump has already infuriated Beijing by questioning longstanding US policy on Taiwan, calling Beijing a currency manipulator and threatening punitive tariffs on Chinese imports.
China's ministry of defence on Saturday had slammed alleged American "hyping" of China's capture of the drone as "inappropriate and unhelpful".
"Trump is not behaving as a president who will become master of the White House in a month. He bears no sense of how to lead a superpower," the often nationalistic Global Times, which has close ties to the ruling Communist Party, said in an editorial.
There are broader tensions in the South China Sea, where China has moved to fortify its claims to the region by expanding tiny reefs and islets into artificial islands hosting military facilities.
Brunei, Malaysia, the Philippines, Vietnam and Taiwan have competing claims in the waterway.
While the US takes no position on sovereignty claims in the area, it has repeatedly stressed freedom of navigation.
Its military has conducted several operations in which ships and planes have passed close to the sites Beijing claims.
"No matter how powerful the US Navy is, it cannot act on the bottom line of China's security," said a second editorial about the probe seizure in the Global Times Monday.
"If we see sonar and underwater gliders deployed by foreign ships in the South China Sea in the future, we would rather mistakenly capture a thousand than miss a single one."