<P> The U.S. believed that North Korea had introduced new weapons contrary to 13 (d), but did not make specific allegations . North Korea also believed the U.S. had introduced new weapons earlier, citing Neutral Nations Supervisory Commission inspection team reports for August 1953 to April 1954 . </P> <P> North Korea denounced the abrogation of paragraph 13 (d). North Korea responded militarily by digging massive underground fortifications resistant to nuclear attack, and forward deployment of its conventional forces so that the use of nuclear weapons against it would endanger South Korean and U.S. forces as well . In 1963 North Korea asked the Soviet Union and China for help in developing nuclear weapons, but was refused . </P> <P> Following the abrogation of paragraph 13 (d), the Neutral Nations Supervisory Commission (NNSC) largely lost its function, and became primarily office based in the DMZ with a small staff . </P> <P> In 1975, the U.N. General Assembly adopted resolutions endorsing the desirability of replacing the Armistice Agreement with a peace treaty and dissolving the UNC . This was followed by North Korean attempts to start peace discussions with the U.S. The U.S. however believed influencing China to restrict North Korean actions would be more effective . </P>

What was one effect of the stalemate in the korean war