SEOUL, March 13 (Reuters) - South Korea should build nuclear weapons to bolster its defences against North Korea, even at the risk of international repercussions, the mayor of its capital city said, arguing that the country cannot be bound by the goal of denuclearisation. commitment or ability to protect the South, a growing number of senior South Korean officials have raised the possibility of developing nuclear weapons or redeploying American tactical nuclear bombs and missiles, which were withdrawn from the Korean Peninsula in the 1990s. In a report this month, Lee Sang-hyun, president of South Korea's Sejong Institute, said that Yoon is not seriously considering a nuclear programme and that a return of American weapons was also unlikely