North Korea fires artillery into sea as South Korea, U.S. pledge co-operation

North Korea fired around 80 artillery rounds into a maritime border zone overnight, South Korea said on Friday, as defence ministers from Seoul and Washington vowed to demonstrate determination in the face of a barrage of missile tests by the North. North Korea fired multiple missiles into the sea on Thursday, including a possible failed intercontinental ballistic missile (ICBM), prompting the United States and South Korea to extend air drills that have angered Pyongyang. Beginning shortly before midnight on Thursday, South Korea's military said it had detected more than 80 artillery rounds fired into the sea by North Korea, in…