Despite the hype around missile defense, particularly THAAD, it has a number very significant limitations that you should be prepared to point out in your debates.
First, despite 100% intercept rates in test conditions when one missile was fired at it, it won’t be able to work in war time conditions, especially when faced with more than one missile.
Ankit Panda, 8-29-17, Can Ballistic Missile Defense Shield Guam from North Korea? https://www.cfr.org/backgrounder/can-ballistic-missile-defense-shield-guam-north-korea
There are considerable risks in both attempting and not attempting to destroy North Korean missiles launched toward Guam. SM-3 and THAAD interceptors have shown success against IRBMs in test environments, in which certain variables are controlled, but they cannot assure defense against multiple North Korean Hwasong-12 missiles in a real attack scenario. The systems have never been tested against multiple missiles simultaneously. Therefore, an attempt to intercept North Korean missiles could fail and, as a result, erode the credibility of U.S. missile defense, even if only one North Korean projectile successfully splashes down near Guam.
Second, the North can just overwhelm the number of interceptors.
Stephen Loacani, 8-30-17, WJLA, As North Korea threat grows, experts warn of weakness in US missile def