China’s navy test-launched a long-range ballistic missile Monday from a nuclear-powered submarine — a move that experts said showed Beijing’s increasing skill and capability as part of its nuclear deterrence strategy. The move also drew protests from the U.S. as well as countries in Asia and the Pacific. It was the second time China had fired a ballistic missile into international waters in recent years. While it gave some countries in the region prior notice, some said it was not enough notice, and experts say the launch exacerbates tensions around increasing militarization in Asia. Here’s what we know, and what we don’t, about the missile launch. China announced the missile test publicly on Monday only after the launch, saying that it was fired into the Pacific Ocean. In a brief statement, the official Xinhua News Agency said the launch was part of routine annual training, complied with international law and practice, and was not directed against any country or target. It didn’t provide details about the type of missile.

Full report : What to know about China’s rare ballistic missile test and why it raises concerns.