S. Korea, Japan, US hold drill against N. Korea submarines

South Korea, Japan and the US held a joint naval exercise Monday aimed at countering missile threats from North Korean submarines, Seoul's defense ministry said, amid mounting concerns over the hermit state's weapons programme.Pyongyang is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five nuclear tests, two of them last year.The three-day drills involving more than 800 troops kicked off after US President Donald Trump