During a military ceremony in South Korea, the country's president delivers a strong message for its neighbour North Korea.<br /> <br />(SOUNDBITE) (Korean) SOUTH KOREAN PRESIDENT PARK GEUN-HYE SAYING<br /> <br />"I will devote all my efforts to making my country strong and prosperous with robust security. I will deal strongly with North Korean provocations."<br /> <br />On Friday, Pyongyang stepped up its threats against South Korea and the United States, declaring that all agreements between the two Koreas would be nullified from March 11.<br /> <br />Seoul's unification ministry urged North Korea to pull back.<br /> <br />(SOUNDBITE) (Korean) SOUTH KOREAN UNIFICATION MINISTRY SPOKESMAN KIM HYUNG-SUK SAYING:<br /> <br />"North Korea should not make inter-Korean relations more difficult by nullifying agreements between two Koreas and they should clearly realise that they cannot get anything with provocations or threats."<br /> <br />South Korea's defence ministry said on Thursday that North Korea has been conducting a series
