On many counts, North Korea’s fifth nuclear test last week means that the world now faces the worst-case scenario: North Korea has -- or is very close to having -- the capability to launch a nuclear strike.

The latest blast, which Pyongyang claimed was a “warhead,” was the most powerful yet -- experts estimate it at a force of at least 10 kilotons of TNT -- and it came only eight months after the previous detonation.

Moreover, the test came as the North is in what seems to be the final stage of completing the development of missiles designed to deliver nuclear warheads. The Kim Jong-un regime test-fired a total of 37 ballistic missiles over the past four years, and claimed recently a successful firing of a submarine-launched ballistic missile. It also fired some missiles on overland mobile pads.

This combination of nuclear and missile technologies should convince us that the 32-year-old Kim -- a notoriously unpredictable, ruthless dictator in the world’s most isolated country -- has the elementary capability for a nuclear strike that could cause an unimaginable catastrophe anywhere he wants.

This reality should change the way the world and South Korea deal with security threats posed by the rogue regime.

President Park Geun-hye has termed the situation a sort of “emergency” that could lead to a war. For the first time regarding the North’s nuclear threat, South Korean officials added “military actions” to options the Seoul government could take in case they detect a sign of an imminent nuclear strike.

US President Barack Obama reiterated Washington’s firm commitment to “extended deterrence.” Democratic presidential candidate Hillary Clinton said that the US needs “rethinking” on its strategy for North Korea.

The UN Security Council, which is already enforcing the toughest sanctions yet on the North, has vowed to take “further decisive action” that forces North Korea to change its position.

There is no doubt that the new UN actions should close the loopholes in the latest UN resolution against the North -- implemented in March -- and make sure China ceases its role as the provider of a lifeline to its impoverished neighbor and client state.

Nevertheless, North Korea is not like Iran and only more international sanctions -- if not something as effective as a total embargo -- would be limited in pressuring the North to give up its nuclear ambitions. 

Here comes the urgent need to secure deterrence against possible nuclear strikes ordered by Kim. One deterrence, according to Seoul officials, is preemptive, South Korea could prepare to make surgical strikes against the North’s nuclear facilities and key sites in Pyongyang, like the office and residence of Kim.

A senior official said that the South Korean military will launch massive strikes that can “remove Pyongyang from map” if there is a sign of an impending nuclear hit from the North.

Given the North’s improved capability -- think about a nuclear-tipped SLBM coming from below the water -- the official’s comments sound like more of a hope than something we can trust blindly. 

Hence there is a pressing need to build up deterrence that could bar the North from making a nuclear strike, or decimate it, in case of an attack.

The first viable option could be the deployment here of US strategic assets -- like stealth bombers, nuclear-powered aircraft carriers and submarines. South Korea is already under the shield of US extended deterrence, but having some of them on stand-by on or near the peninsula -- instead of places like Guam -- would send an utterly different message to the North.

This is because South Korea would not be able to put up defensive measures, like kill chain or Korean Air and Missile Defense system, until the early 2020s. 

A more effective strategy -- also a much more controversial one -- would be the redeployment of US nuclear tactical weapons which were withdrawn from the peninsula in the early 1990s. Some raise concerns about its implications, but it should be noted that there is a growing call for developing nuclear arms on our own.

Needless to say, the nuclear threat from the North is a matter of life and death for us South Koreans. We cannot be bound by taboos or other restrictions if what we are about to do could determine the fate of ourselves and our descendants.