Thousands of South Korean protesters waved flags and shouted slogans Friday as they demanded their country cut off aid and investment to North Korea to punish the communist nation for reportedly testing a nuclear device. "We are facing the most dangerous time since the end of the Korean War," said former lawmaker Lee Cheol-seung at the demonstration, which comprised mostly retirees and veterans. The protest - which police said drew about 3,000 people - came as the United Nations considered sanctions against North Korea for its proclaimed nuclear test on Monday. The United States and Japan have been pushing for tough measures, but South Korean political parties have disagreed over their country's policy.