In May, it was announced that the United States was “disinviting” China from participating in the annual Rim of Pacific (RIMPAC) training exercise that aims to increase interoperability between allies national Navies in the Pacific. At the time, the U.S. cited China’s aggressive behavior in the South China Sea, rapidly expanding their military presence and making declarations of sovereignty over international waters that American officials characterized as “running counter to international norms.” Lt. Col. Christopher Logan, a Defense Department spokesperson, said at the time,

The United States is committed to a free and open Indo-Pacific. China’s continued militarization of disputed features in the South China Sea only serve to raise tensions and destabilize the region. As an initial response to China’s continued militarization of the South China Sea we have disinvited the PLA Navy from the 2018 Rim of the Pacific (RIMPAC) Exercise. China’s behavior is inconsistent with the principles and purposes of the RIMPAC exercise.”

The announcement came as little surprise — although China has participated in elements of the RIMPAC exercises of the past, China’s efforts to lay claim to what is perhaps the most heavily traversed waterway on the globe has been the root of rising tensions between the two nations for some time. Despite China’s invitation being revoked, this year’s RIMPAC wasn’t hurting for participants, with 46 vessels hailing from 25 nations participating, along with more than 200 aircraft, five submarines, and an estimated 25,000 people. However, on Friday, the U.S. Navy confirmed that at least one ship from the Chinese People’s Liberation Army-Navy (PLAN) found its way to the drills — an auxiliary general intelligence (AGI) ship that likely belongs to their Dongdiao-class of spy ships.

“It is very disappointing that the presence of a non-participating ship could disrupt the exercise,” Chilean Navy Commodore Pablo Niemann said to journalists regarding China’s decision to send a ship to monitor the RIMPAC exercises. “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 presence of the ship likely won’t interfere with the exercise, as China’s presence in the region, although distracting, is likely intended as an observational one — RIMPAC offers China the opportunity to see how vessels from multiple foreign Navies operate as well as how international partners work in sync with one another. The intelligence they’ll be able to gather through routine monitoring of the event alone could be extremely valuable to the development of their own maritime doctrines, as well as the development of strategies aimed at countering the presence of many of those national forces in the Pacific. U.S. Pacific Fleet spokesman Capt. Charlie Brown said,

We expect the ship will remain outside the territorial seas of the U.S. and not operate in a manner that disrupts ongoing RIMPAC exercise. We’ve taken all precautions necessary to protect our critical information. The ship’s presence has not affected the conduct of the exercise.”

The Dongdiao-class, also known as the Type 815 spy ship, is China’s most advanced electronic reconnaissance ships. Weighing in at nearly 6,100 tons, the nearly 400 foot long ships carry a crew of 250 and house not only advanced electronic espionage systems but come armed with one 37 millimeter and two 14.5 millimeter guns. The ship is capable of conducting “round the clock surveillance” on multiple different targets across a large expanse of open sea, according to claims made in Chinese media in recent years.

Featured image: The U.S. Navy Ticonderoga-class guided missile cruiser USS Port Royal (CG 73), the Mexican Navy patrol-vessel ARM Revolution (P 164), the People’s Liberation Army (Navy) frigate Yueyang (FF 575) and destroyer PLA(N) Haikou (DD 171) move into a multi-ship formation during Rim of the Pacific (RIMPAC) Exercise 2014. Twenty-two nations, 49 ships, six submarines, more than 200 aircraft and 25,000 personnel are participating in RIMPAC from June 26 to Aug. 1 in and around the Hawaiian Islands and Southern California. The world’s largest maritime exercise, RIMPAC provides a unique training opportunity that helps participants foster and sustain the cooperative relationships that are critical to ensuring the safety of sea lanes and security on the world’s oceans. RIMPAC 2014 is the 24th exercise in the series that began in 1971. | U.S. Navy photo by Mass Communication Specialist 2nd Class Corey T. Jones/Released