North Korea fired two missiles with a range of about 500 kilometers into the East Sea on Thursday. The latest provocation came one week after it sent rockets into the sea hours after the U.N. imposed new sanctions against its latest nuclear test and ballistic missile launch.

These are part of the rogue regime’s usual responses to outside pressure like the international sanctions, which come amid the largest-ever South Korea-U.S. joint military drills.

While these traditional provocations should not be overlooked, there is a bigger cause for concern. The North keeps heightening the threat of its nuclear prowess.

North Korean leader Kim Jong-un, who had ordered to put nuclear arms on standby for attack at any time, went on to claim that the country has small, light nuclear warheads that could be mounted onto ballistic missiles.

The Rodong Sinmun newspaper, showing a photo of Kim speaking with what it said were nuclear scientists, quoted him as saying that he was pleased that they have succeeded in standardizing the small warheads. It carried a photo of what is believed to be a model of the warhead -- a globe-shaped silver object. “This can be called true nuclear deterrent,” Kim was quoted as saying. 

On Friday, the North’s state media reported that Kim ordered more nuclear tests and diversification of the means for delivering nuke warheads so as to “make nuclear strikes at the enemies from anywhere on the ground, in the air, at sea and underwater.”

Experts and military officials seem split -- as they did when the North claimed it detonated a hydrogen bomb for its fourth nuclear test Jan. 3 -- over the claim of obtaining miniaturized warheads.

Of course, it could be another mock-up or bluffing, which are typical of the isolationist rogue regime. The North indeed is good at manipulating photographs. 

Nevertheless, its claim of possessing missile-tipped nuclear warheads should never be taken lightly. Some experts cast doubts that the North has any such operable devices. But none of them have evidence that it does not.

It has been 10 years since the North detonated its first nuclear bomb, and thenceforth it has striven to enhance its atomic devices and lengthen the range of ballistic missiles.

The North must have achieved progress in both areas. It has conducted four nuclear tests and claims that it successfully test-fired a submarine-launched ballistic missile. It is truly worrisome if Kim Jong-un has in his hands a nuclear-tipped SLBM which can hit any target in the South.

The recent developments surrounding the North’s weapons of mass destruction call on the South Korean and U.S. military and intelligence authorities to bolster their spying operations to assess the North’s WMD capabilities.

It is also important to enhance the allies’ missile defense capability and readiness to make preemptive strikes against the North’s missile and nuclear sites. When it comes to security, one should always think about the worst-case scenario.

What’s deplorable is that the North still does not realize the situation is different from the past. One example is the fact that China and Russia have joined the toughest-ever U.N. sanctions on the Pyongyang government.

As the sanctions take effect one by one, the North Korean economy, which is already in dire straits, will plunge into deeper troubles. Resorting to saber rattling and threat of nuclear attacks will neither alleviate the economic difficulties nor guarantee its survival. Only giving up the WMDs and coming back to the negotiation table will do.