North Korean leader Kim Jong Un’s denunciation of “dangerous” U.S.-ROK nuclear moves and threat to retaliate with “special assets” has ramped up the regime’s rhetoric even as the allies entertain diplomacy, experts say, driving home that denuclearization is off the table for any negotiations.

In a speech at a major weapons expo over the weekend, Kim accused the U.S. of carrying out a military buildup aimed at facilitating “preemptive strikes” in the event of a contingency, while arguing that Washington and Seoul have established a “nuclear alliance.”