South Korea has just entered the planet's most exclusive club, and China and North Korea are not exactly calm

South Korea has launched the Jangbogo-N project to build nuclear-powered submarines.

Seoul says stronger undersea deterrence is needed to counter North Korea’s advancing military capabilities.

The move could shift the naval balance in East Asia by giving South Korea a more persistent, harder-to-detect capability.

China is watching closely, as the program raises regional competition and nonproliferation concerns.