North Korea has fired a submarine-launched ballistic missile into the sea off the east coast of the peninsula, according to South Korea and Japan. If confirmed, it would be the latest in a series of missile tests by Pyongyang. It comes just days before the inauguration of South Korea"s new president, Yoon Suk-yeol, who has vowed to take a firmer line with the North. The Japanese defense minister called the launch an unacceptable threat to the international community. The minister, Nobuo Kishi, also told reporters that Japan would continue to "strengthen defense capabilities drastically". On Friday, the US State Department warned that North Korea could be preparing to conduct a nuclear weapons test, its first in five years. The BBC"s Jean Mackenzie in Seoul said the timing of the latest launch is particularly significant and puts pressure on the incoming South Korean leader. He is due to be sworn into office on Tuesday and is scheduled to meet US President Joe Biden in Seoul on May 21. US and South Korean intelligence sources believe a North Korean nuclear test could come in between those two events. Last month, North Korean leader Kim Jong-un pledged to step up his country"s nuclear weapons program. He was speaking at a huge military parade to mark the armed forces" founding anniversary, at which banned intercontinental ballistic missiles were displayed. — BBC