The South Korean military has called for preparedness to face any kind of biochemical weapons threat from North Korea. The call has come within days of the high-profile assassination of Kim Jong-nam, the estranged half-brother of North Korean leader Kim Jong-un.

Seoul claims Pyongyang is thought to be operating a regiment-level biochemical weapons unit in order to mount an assault on it adversaries. The military warned that unconventional attacks could be underway, prompting it to draft plans to step up its detection capabilities.

Kim was assaulted by two female assassins at the Kuala Lumpur International Airport on 13 February. They were widely believed to have acted on the orders of the regime in Pyongyang. He died within 20 minutes of the incident and forensic investigations have found that the attackers used the deadly VX nerve agent, classified by the UN as a weapon of mass destruction.

During high-level security talks on Monday, 27 February, with ruling party officials, the South Korean defence ministry cautioned that the North has a massive stockpile of chemical and biological weapons which could be put to use anytime.

It is believed to possess the world's third largest chemical weapons stockpile — anywhere between 2,500 and 5,000 tons of deadly chemical warfare agents which are officially banned under international regulations.

Until Kim's killing in mid-February, there was no evidence of North Korea, which is not a signatory to the Chemical Weapons Convention, having access to the VX nerve agent.