An unspecified two-seater Chinese fighter jet crashed into the South China Sea on Tuesday while conducting training operations near the island of Hainan. According to the limited details released by the People’s Liberation Army, both pilots died in the incident.

According to official reports, the aircraft crashed in Ledong County of the Hainan Province, one of a number of islands in the South China Sea the nation has militarized in order to further justify and potentially defend China’s claims of sovereignty over the majority of the waterway. A video uploaded to YouTube shortly after the crash reportedly shows its aftermath, but does little to clarify what type of aircraft was involved.

Despite the limited details available, it seems entirely plausible the type of fighter that went down may have been the People’s Liberation Army-Navy’s workhorse J-15. The platform, which is largely based on the Russian Sukhoi Su-33, was developed by reverse-engineering an unfinished prototype of the Russian jet acquired from Ukraine in 2001. However, the J-15 is notably heavier and has a far worse track record than the Russian jet it was based upon.

“Years ago, the Chinese decided to save some money and, instead of buying several Su-33s from Russia for their subsequent license production in China, they opted for a Su-33 prototype in Ukraine,” Russian military analyst Vasily Kashin was quoted as saying in a Russian media piece accusing China of design theft.

“As a result, the development of the J-15 took more time and more money than expected, and the first planes proved less than reliable,” he said.

Last year, reports began to emerge about China’s trouble with the J-15, which included a number of crashes, some of which were not reported by Chinese media outlets that are beholden to the nation’s government. As China’s primary carrier-based fighter, the J-15 plays an important role in the nation’s force projection capabilities, though at this point, even the PLA acknowledges plans are moving forward to replace it.

With only around 20 or so total J-15s built in China, the platform has already seen four unconfirmed crashes, though Chinese authorities have only acknowledged two. There are one- and two-seater variants of the platform, meaning Tuesday’s crash could potentially have been China’s troubled Navy fighter. The question is, will China choose to acknowledge it or not?