The article discloses that the Obama administration has escalated its nuclear threat to the DPRK year by year.

In this period the U.S. staged madcap drills for a preemptive nuclear strike at the DPRK by amassing all types of strategic nuclear strike means around the Korean peninsula.

What merits a serious attention is that the U.S. warmongers staged the largest-ever war maneuvers in the most undisguised manner, talking about "operations for occupying Pyongyang" and "beheading operation" after completely discarding the veil of "annual" and "defensive" drills much touted by them.

The U.S. worked hard to deprive the DPRK of its sovereignty and right to self-defense and its people of even the right to existence in wanton violation of international law while taking issue with the DPRK's every measure for bolstering up its nuclear deterrence.

Obama has been engrossed in unprecedented political and military pressure and sanctions while trampling down international law and justice. His ulterior motive was to disarm the DPRK and justify the U.S. unilateral nuclear threat and preemptive strike.

However, he was sadly mistaken.

During the Obama administration the DPRK registered spectacular successes in its four nuclear tests.

The DPRK emerged a full-fledged nuclear power possessed of tremendous nuclear strike capability despite the U.S. persistent unprecedented nuclear threat and blackmail and sanctions.

The U.S. can hardly guarantee the security of its mainland as it may be reduced to debris in a moment if it launches aggression against the DPRK.