The Chinese and U.S. militaries are having "unimpeded" talks about the return of U.S. underwater drone taken by a Chinese naval vessel in the South China Sea last week, China's foreign ministry said on Monday.
The drone, known as an unmanned underwater vehicle (UUV), was taken on Thursday in waters off the coast of the Philippines, the first seizure of its kind in recent memory.
The Pentagon went public with its complaint about the incident and said on Saturday it had secured a deal to get the drone back. China's defense ministry had earlier accused Washington of hyping up the issue.
"What I can tell you is that at present, China and the United States are using unimpeded military channels to appropriately handle this issue," foreign ministry spokeswoman Hua Chunying told a regular briefing.
U.S. President-elect Donald Trump, who has vowed to take a more aggressive approach in dealing with China over its economic and military policies, jumped on the unusual seizure with a pair of provocative tweets over the weekend, accusing Beijing of stealing the equipment.
Asked about Trump's comments, Hua said describing the drone as stolen was "completely incorrect".
"The key is that China's navy had a responsible and professional attitude to identify and ascertain this object," she said. "If you discover or pick something up from the street you have to examine it and if somebody asks you for it you have to work out if it's theirs before you can give it back."
The drone, which the Pentagon said was operating lawfully was collecting data about the salinity, temperature and clarity of the water about 50 nautical miles northwest of Subic Bay, off the Philippines.
The Philippines said the occurrence of the incident inside its exclusive economic zone (EEZ) was "very troubling".
"Not only does it increase the likelihood of miscalculations that could lead to open confrontation very near the Philippine mainland but the commission of activities other than innocent passage which impinge upon the right of the Philippines over the resources in its EEZ are violations of the Philippines rights over its EEZ," Defence Minister Delfin Lorenzana said in a statement.
China is deeply suspicious of any U.S. military activities in the resource-rich South China Sea, with state media and experts saying the use of the drone was likely part of U.S. surveillance efforts in the disputed waterway.
The overseas edition of the ruling Communist Party's People's Daily said in a commentary on Monday the USNS Bowditch, which was operating the drone, was a "serial offender" when it came to spying operations against China.
"The downplaying of the actions of the drone cannot cover up the real intentions in the background," it said. "This drone which floated to the surface in the South China Sea is the tip of the iceberg of U.S. military strategy, including toward China."
The USNS Bowditch is an "infamous" military reconnaissance ship that has been surveying China's coastal waters since 2002, said Ma Gang, a professor at the People's Liberation Army National Defence University, told the official China Daily.
"Oceanic data is crucial for ship formations, submarine routes and battle planning," Ma said. "Therefore, it is normal for the Chinese Navy to be suspicious of Bowditch's activities given past experience."
According to Chinese state media, the same ship was involved in incidents in 2001 and 2002 when it was shadowed by Chinese navy ships while operating in the Yellow Sea. Chinese media say it has also operated in the sensitive Taiwan Straits.
Ni Lexiong, a naval expert, Shanghai University of Political Science and Law, told Reuters he believed the Chinese navy probably had orders to take the drone.
But Ni said this is a very different incident from the 2001 intercept of a U.S. spy plane by a Chinese fighter jet that resulted in a collision that killed the Chinese pilot and forced the American plane to make an emergency landing at a base on Hainan.
"This is a much smaller incident, it won't affect the overall picture of China-U.S. relations," he said, adding that he did not expect China to seek an apology from the U.S.
The 24 U.S. air crew members were held for 11 days before being released, souring U.S.-Chinese relations in the early days of President George W. Bush's first administration.