Models of a mock North Korea Scud-B missile, center right, and other South Korean missiles are displayed at Korea War Memorial Museum in Seoul, South Korea, Sunday, March 17, 2013. A South Korean military official said Saturday North Korea launched what appeared to be KN-02 missiles last week during its own drills. He won't say on what day it happened. Models of a mock North Korea Scud-B missile, center, and other South Korean missiles are displayed at Korea War Memorial Museum in Seoul, South Korea, Sunday, March 17, 2013. He won't say on what day it happened. (AP Photo/Ahn Young-joon) WASHINGTON (AP) - The chairman of the House Intelligence Committee says the U.S. just doesn't know about "the stability" of North Korea's young leader, who has threatened pre-emptive nuclear attacks on Washington. Republican Rep. Mike Rogers of Michigan says Kim Jong Un is trying to "prove himself" to his military and the military is eager for "saber-rattling" for its own self-interest. North Korea also has said recently that it no longer will recognize the armistice that ended the 1953 Korean War. The Pentagon said Friday that it will spend $1 billion to add 14 interceptors to an Alaska-based missile defense system, responding to what it called faster-than-anticipated North Korean progress on nuclear weapons and missiles. Rogers tells CNN's "State of the Union" that the North Koreans seem to be looking for some "provocations."