North Korea's plan to attract foreign investment by setting up economic development zones is doomed to fail unless Pyongyang addresses its nuclear weapons programs, a senior South Korean official said Thursday. Ju Chul-ki, senior presidential foreign affairs secretary, said in a forum that no one can invest in North Korea properly while tightened U.N. sanctions remain in place against the country for its nuclear tests. North Korea conducted nuclear tests in 2006, 2009 and February 2013, drawing international condemnation and tougher U.N. sanctions. Still, North Korea has said it will simultaneously pursue both nuclear and economic development, calling its nuclear programs a deterrent against what it claims is the United States' hostile policy against it. South Korea and the U.S. warned that the North's policy is a dead end for the country. Ju also called on North Korea to follow in the footstep of either Ukraine or Kazakhstan in giving up nuclear weapons in return for economic aid and security guarantees. North Korea has rejected previous calls to emulate Libya, which received a set of political incentives after abandoning its nuclear program.