Transcript for Tensions ratchet up between North Korea and the United States

In for David. We begin with the rising tensions. North Korea and the united States, backed up by powerful arsenals, exchanging dangerous threats. Tonight, new images of the 22,000-pound bomb American forces dropped on Afghanistan. And an aircraft carrier and Navy strike group headed that way. Martha Raddatz in Seoul, south Korea, tonight. Reporter: Tonight, amid mounting tensions with the United States, North Korea's unpredictable leader Kim Jong-un greeted with thunderous applause by his nation's military brass. Tomorrow, the hermit kingdom celebrates the 105th anniversary of the birth of its founder, Kim il-sung. Crowds already gathering in Pyongyang. Events like these, typically marked with a show of military might, weapons on parade. And also missile launches. Tonight, fear something even more sinister may be in the store, that North Korea will conduct an underground nuclear test. It comes during an escalating standoff between Kim's regime and the white house. Today, a top north Korean official tells the associated press the trump administration is "More vicious and more aggressive" than its predecessor. Reporter: "Trump is always using aggressive words," he says, singling out the president's tweets. "It is the U.S. That is threatening us." Ooifr I've had meetings on North Korea. He's acting very, very badly. I will tell you. He's acting very badly. Reporter: President trump has often tweeted about the, quote, "Menace of North Korea." "North Korea is looking for trouble," he wrote. "They have been playing the United States for years." He has promised to, quote, "Solve the problem." Yesterday, when the U.S. Dropped the mother of all bombs on ISIS caves in Afghanistan, the president was asked if it was a message to North Korea as well. I don't know if this sends a message. It doesn't make any difference if it does or not. North Korea is a problem. The problem will be taken care of. Reporter: The U.S. Now sending the aircraft carrier, the "Uss Vinson" into the region. American troops conducting military exercises on the border. North Korea now reportedly calling the administration's words and actions "Maniacal military provocations." And this threat, "We will go to war, if they choose." Adding, they could destroy major American military bases in south Korea "Within minutes." Tonight, China warning of, quote, "Gathering storm clouds," saying, "We urge all parties to refrain from inflammatory or threatening statements or deeds." Hoping a war of words doesn't escalate into the real thing. And Martha joins us now. You mentioned China's warning in your story, but they're also offering assistance? Reporter: That's right. China is hoping to help resume a dialogue with the north, and vice president pence is arriving here in Seoul this weekend. Tom? Martha, leading us off tonight. Thank you. As the tensions with north Korea ratchet up, president trump is back with mar-a-lago. David Wright, how will the president monitor developments in Florida? Reporter: The white house tells us he's getting regular updates, but he's here without virtually all of his top advisers. And there are questions about whether mar-a-lago is secure enough to handle a crisis. Remember the pictures taken by club guests? Last week, a very different picture. The president and his advisers in a makeshift situation room. Bottom line, the president is able to monitor and react as needed from here. Tom? Thank you. Next to the fallout from the

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