China was disinvited from the prestigious Rim of the Pacific exercise, but it has made an appearance anyway — dispatching a spy ship to international waters off Hawaii, the Navy said Thursday.

Chilean Commodore Pablo Niemann, the combined forces maritime component commander for this year’s RIMPAC, said he was disappointed.

“My team and I have been working on the construct and planning of RIMPAC 2018 for more than a year, a plan which has been built considering all of the 25 participating nations and their national training objectives,” Niemann said in a statement.

As maritime commander, Niemann said “it is very disappointing that the presence of a non-participating ship could disrupt the exercise. I hope and expect all seafarers to act professionally so we may continue to focus on the work at hand and building on the spirit of cooperation that gives purpose to this exercise.”

The Navy confirmed that a People’s Liberation Army Navy auxiliary general intelligence, or AGI, ship was detected off Hawaii coinciding with the early phase of the at-sea portion of the world’s largest international maritime exercise.

In 2014, the first time China was invited to participate in RIMPAC, it also sent a spy ship. The Navy had previously confirmed that China sent a surveillance ship near Hawaii in 2012 as well.

In 2016 during RIMPAC, a Russian Balzam-class auxiliary general intelligence ship arrived in international waters off Hawaii.

The exercise is held every other year.

“Obviously, we are aware that it is there, and we’ve taken all precautions necessary to protect our critical information,” U.S. Pacific Fleet said at the time. “Its presence has not affected the conduct of the exercise.” Russia last participated in RIMPAC in 2012.

China was invited and had indicated it would participate in the current RIMPAC, but that invitation was rescinded in May over its ongoing militarization of man-made islands in the South China Sea. China also was labeled a strategic competitor of the United States.

Retired Navy Capt. Carl Schuster, a former director of operations at U.S. Pacific Command’s Joint Intelligence Center and an adjunct professor at Hawaii Pacific University, said China’s uninvited presence is more than a poke in the eye to the United States.

“It’s actually intelligence-gathering,” Schuster said, adding “it’s something that any prudent country would do, although it always has a political element to it.”

“But an AGI is looking at how we do tactics, how we do procedures; they are also monitoring all the radar signals, because there are very few opportunities these days to see every country’s radar and systems in play,” Schuster said.

Twenty-five nations, 46 surface ships, five submarines, 18 national land forces, more than 200 aircraft and 25,000 personnel are gathered mainly in Hawaii but also in Southern California for RIMPAC.

Schuster called it an “intelligence opportunity that’s hard to turn down.”

The United States can counter China’s information-gathering to some extent, Schuster added.

“There are things that you can do to give them a false picture,” he said, “but it takes a lot of effort, No. 1, and you just have to accept the fact that some of the things you do you can’t change, and they’re probably going to collect it.”