"I instruct the military, foreign and other related ministries to maintain our solid defense posture under the grave situation before and after the presidential election, and strengthen cooperation with the international community," Hwang was quoted as saying by Yonhap news agency.
Hwang stressed that Pyongyang was continuing to carry out provocations, which threatened stability of the region.
"The North's continued provocations are threatening the peace and stability of the Korean Peninsula and the international community, and if it carries out additional provocations, it will face economic and diplomatic sanctions different from what has been taken so far," he added.
The situation on the Korean peninsula aggravated in recent months as North Korea carried out a number of missile launches and nuclear tests.
The most recent missile test allegedly took place on Saturday from a site north of Pyongyang. Japan, South Korea and the United States said the test appeared to have failed as the missile broke up within North Korean territory.
The South Korean election is slated for May 9. It comes less than two months after President Park Geun-hye was ousted following a corruption scandal that also led to her arrest.
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