German Foreign Minister Guido Westerwelle called on both sides of the Korean Peninsula to exercise "utmost prudence," his spokesman Andreas Peschke said Wednesday. Germany stood firmly by South Korea and criticized North Korea's decision to restart a closed nuclear reactor. "That is a further escalation that will make an already dangerous situation much more difficult and dangerous," Petschke was quoted as saying by DPA. Westerwelle also appealed to China's leaders to use their influence to help quell North Korean aggression, he said.