China has found itself involved in another dustup in the South China Sea, as their current amphibious assault rehearsals and live-fire maritime exercises in the region have drawn Vietnam’s ire.

Vietnamese authorities, believing that China’s presence in those waters violates their sovereignty, issued a statement demanding that the exercise be halted. On Tuesday, after Vietnam had already lodged their complaint, China’s navy — the People’s Liberation Army Navy (PLAN) — took things a step further, beginning live-fire drills that involved at least 100 naval vessels and dozens of aircraft, and during which thousands of shells and dozens of missiles and torpedoes were fired.

Part of the problem, as far as Vietnam is concerned, is that they hold claim to the nearby Paracel Islands, and the surrounding waters. But their complaint doesn’t hinge solely on contested waters, per se — though most of China’s claimed islands and waters in the South China Sea are contested by one country or another. Rather, Vietnam is peeved because, on July 20, only two days before their exercise was to begin, China issued a statement declaring that no other vessels would be allowed in the area for the duration of their maneuvers.

Sending out warnings about impending military drills and shooing away civilian vessels is standard practice (and very good manners) in most situations. But when that no-go zone is extended into international waters or what you consider to be your territory, it’s considered very rude indeed.

Read more: https://news.vice.com/article/vietnam-is-pissed-that-china-is-blowing-up-the-south-china-sea