China has sent a spy ship to international waters off Hawaii during a giant U.S.-led naval exercise involving 22 countries, even as Beijing participates in the drills for the first time this year, the U.S. Navy said on Sunday.
The Navy played down any U.S. intelligence risk associated with the proximity of the Chinese surveillance vessel and noted that China also sent a similar ship to monitor the last Rim of the Pacific (RIMPAC) exercise two years ago.
"We've taken all necessary precautions to protect our critical information," said Captain Darryn James, chief spokesman of the U.S. Pacific Fleet.
"We expect this ship will remain outside of U.S. territorial seas and not operate in a manner that disrupts the ongoing Rim of the Pacific maritime exercise."
There was no immediate comment from Beijing.
U.S. officials hope China's participation in RIMPAC helps avert misunderstandings on the high seas but analysts long cautioned the maneuvers may ultimately help Beijing strengthen its growing naval capability by observing the forces of the United States and its allies.
Still, the United States also conducts surveillance operations in international waters and airspace and the Navy did not voice protest over the appearance of the Chinese vessel, described as a Chinese Navy auxiliary general intelligence ship.
Even though the vessel was inside America's 200-nautical mile exclusive economic zone, it was operating within international law, James said.
Still, James said he was unaware of any participant doing something similar since the drills began in 1971.
"To my knowledge, this is the first time a nation has ever sent a surveillance ship near Hawaii while also having invited ships participating in the RIMPAC exercise," James said.
The Chinese ships participating in the drills are the missile destroyer Haikou, the missile frigate Yueyang, the supply ship Qiandaohu and the hospital ship Peace Ark.
Chinese forces include two helicopters, a commando unit and a diving unit, a total 1,100 personnel.
The exercises come at a time when tensions are high between Beijing and U.S. allies such as Japan and the Philippines over China's pressing of territorial claims in the South and East China Seas.
They also come after a dispute with Vietnam that led to one of the worst breakdowns in ties since they fought a brief war in 1979.