However, the DPRK vigorously advances along the road it chose, under any grave situation caused by the U.S.-led imperialists, drawing deep attention of the international community.

In this regard, a Russian personage said: The harsher the U.S. clamps pressure, the stronger the DPRK people become and the more the U.S. gives nuclear threats, the stronger the DPRK people's striking capability grows, like Newton's third law of motion. This can be called "DPRK's political dynamics".

In actuality, the DPRK has answered a wave of U.S. challenges with its toughest counteractions.

The DPRK successfully carried out three rounds of nuclear tests to bolster up its nuclear deterrent in reaction to the sanctions and pressure tightened by the U.S. over its satellite launch for peaceful purpose.

Obama's recent tour of Asian region including south Korea for the U.S. Asia-Pacific strategy aimed at domination over the region sparked off another round of nuclear face-off between the DPRK and the U.S. He termed the defensive measures taken by the DPRK "provocation" and "threat", while crying out for harsher sanctions and pressure and "use of military force".

But the DPRK clarified its stand that it would continue bolstering up its nuclear deterrent and there is no statute of limitations to its declaration that it would not rule out a new form of nuclear test.

The U.S. policy-makers should ponder over the disastrous consequences to be entailed by the DPRK's exercise of the inviolable right to self-defence.