Former US President Jimmy Carter and three elder statesmen today began their three-day visit to North Korea amid a flurry of diplomatic efforts to ease tensions on the Korean Peninsula and revive stalled international talks on the North's nuclear weapons programs.

Security of the state internet network being used by Central and local administrations will be beefed up, the home affairs ministry said today, after the country came under a massive cyber attack, known as the distributed denial-of-service (DDoS) attack, early in March.

For the second straight year China has emerged as the world's leading shipbuilding nation and is way ahead of S. Korea which has come a distant second, data showed.