South Korean marines storm the beach as smoke screens explode above them during a military exercise with the United States in Pohang on Monday. The same day, South Korea exchanged fire with North Korea, who is threatening a fourth nuclear test, in the Yellow Sea, a violent sign of increased tension between two countries that are still technically at war. Meanwhile, North Korea says it will conduct live fire drills near the border. [Gizmodo en Español]

Images via AP