South Korea\'s customs office said Thursday it will beef up efforts to tighten security at the nation\'s main gateways in a bid to guarantee the safe hosting of a large-scale global nuclear security meeting to be held here next month. South Korea will host the Nuclear Security Summit on March 26-27 in Seoul. It is expected to bring leaders and other ranking officials from more than 50 nations and global organizations to the capital. Yonhap, quoting South Korean officials, said security for the summit would include about 40,000 police officers and an undisclosed number of troops. Leaders of about 50 countries, including U.S. President Barack Obama, are expected at the summit, designed to strengthen international safeguards and help prevent nuclear terrorism, Yonhap reported. The first summit was held in 2010 in Washington. \"We will never overlook such [a] nuclear confab doing harm to the dignified [North Korea],\" the North Korean peace committees said, vowing to \"decisively smash\" the anti-North \"nuclear racket by disturbers and wreckers of peace.\" In reaction, in Pyongyang, North Korea issued a stern warning against South Korea hosting next month\'s Nuclear Security Summit, calling it a provocation. The North Korean Central News Agency quoted three committees on peace as saying in a joint statement the summit set for March 26 in Seoul would be an \"intolerable, grave provocation,\" Yonhap news agency reported. The report said the North Korean warning came a day after KCNA reported the country\'s new leader Kim Jong Un had inspected a military base believed to oversee missile units.