South Korea's top naval officer on Tuesday called for watertight vigilance against any possible North Korean provocations following the assassination of its leader Kim Jong-un's half-brother Kim Jong-nam.

Chief of Naval Operations Adm. Um Hyun-seong visited troops on two border islands of Udo and Yeongpyeong in the West Sea.

"The murder of Kim Jong-nam clearly shows the regime's brutality and recklessness. The current security situation on the Korean peninsula and the region is at risk," the flag officer said in the statement.

In this photo taken on Feb. 21, 2017, Chief of Naval Operations Adm. Um Hyun-seong calls for readiness against North Korean provocations in the northern border island of Yeonpyeong. (Yonhap)
Seoul officials believe North Korea is behind the murder of Kim Jong-nam, 46, in Malaysia last week. He had spoken out publicly against his family's dynastic control of the rogue regime.

A day earlier, Defense Minister Han Min-koo called for readiness against any possible military attacks by the North during his visit to the Marine Corps headquarters in Hwaseong, just south of Seoul.

South Korea's military has repeatedly vowed it will strongly retaliate against any provocations by Pyongyang to avenge the deaths of 50 South Koreans who were killed in two separate surprise attacks carried out in March and November of 2010. (Yonhap)