2009. for some perspective, that's about 2/3 the size of the bomb dropped on hiroshima. news of this test immediately sent u.s. and south korea forces in the region on high alert. here in japan, the prime minister convened an emergency security meeting. the key question, how big was the bomb detonated and did they use plutonium. or highly enriched you main rum? north koreans claim it was a lighter atomic bomb, meaning a greater chance for this bomb to be weaponized. analysts say if north korea were successful in build thing bomb out of highly enriched uranium, it would speed up pyongyang's ability to extend its arsenal in a relatively short amount of time. rob and diana? >> akiko, you mentioned that the u.n. security council will hold an emergency meeting on all of this in the morning. so what exactly could they do? i assume it could be more sanctions? >> reporter: we could certainly expect more sanctions. here in japan, we've heard from