During an Armed Forces Day ceremony, Park said the security situation on the Korean Peninsula and in Northeast Asia was "very grave" because of North Korea's pursuit of nuclear weapons development to build more sophisticated bombs, Yonhap news agency said.
"We have to build strong deterrence against North Korea until the North abandons its nuclear program and makes the right choice for the people of North Korea and peace on the Korean Peninsula," Park said at an airbase in Seongnam.
While maintaining a strong defense system jointly with the United States, Park said, South Korea will secure weapons capable of destroying weapons of mass destruction.
South Korea's defense systems will force North Korea to realize "on its own that its nuclear weapons and missiles ... are useless," she said.
"Only when we are backed by strong national defense that does not allow provocations can we bring North Korea onto a genuine path of change," Park said. "I hope you will do your duties with a mindset that the country's fate and unification of the Korean Peninsula hinge on the shoulder of every member of the armed forces."
Yonhap said the direction of the alliance between Seoul and Washington is expected to dominate discussions during a Security Consultative Meeting between U.S. Defense Secretary Chuck Hagel and his Korean counterpart Kim Kwan-jin Wednesday.