China just ran into a problem with its only friend in the South China Sea

China has just had a run-in with its only friend in the South China Sea, and that could complicate matters for Beijing as it continues to try to take a more aggressive stance in the region.

On March 19, an official Indonesian vessel detained a Chinese fishing trawler that was operating in Indonesia's exclusive economic zone (EEZ) off the coast of the Natuna islands.

The islands are on the periphery of the South China Sea, and their EEZ abuts China's self-declared Nine-Dash Line, which Beijing uses to mark its claims in the region.

In the past, Indonesia has not had any issues with China's increasingly aggressive actions in the region. However, after Jakarta seized the Chinese trawler, things got awkward quickly for the two nations.

While towing the Chinese vessel toward the Natuna islands, a Chinese coast guard ship rammed the Indonesian vessel in an attempt to free the Chinese boat, Bloomberg reports.