North Korea gives John Kerry his first "3 AM" call

security

By Elise Labott, with reporting by Barbara Starr

North Korea's nuclear test set off a diplomatic scramble for America's new Secretary of State as the U.S. national security community began working with other countries to try and determine what North Korea truly achieved. The test was was not a total surprise, senior administration officials said. North Korea warned the United States and China on Monday that it would be undertaking a nuclear test, two senior administration officials tell CNN. The warning came in the form of a message through the “NY channel,” which is the U.S. mission to the United Nations. This is the typical way North Korea passes messages to the United States. The warning was not specific on timing, but the officials said the U.S. took it to mean the test could happen at any moment. After the test was detected late Monday night, Secretary of State John Kerry spoke with South Korea's foreign minister. He is also expected to talk with Chinese, Japanese, Russian ministers. The U.S. began coordinating its own response with inter-agency calls between Washington and Seoul, Tokyo, Moscow and Beijing. US Ambassador to South Korea Sung Kim and General James Thurman, Commander of the US-ROK Combined Forces Command, met with the South Korean defense minister. The U.S. intelligence community and military began the process of assessing the test and North Korea's claims and by morning concluded an underground nuclear test had probably been conducted. World reaction to the test "The explosion yield was approximately several kilotons. Analysis of the event continues." according to a statement released Tuesday by the Office of the Director of National Intelligence. Nuclear monitoring by the Comprehensive Test Ban Treaty Organization will calculate what was released by the explosion. The U.S. will likely try to get additional readings from aircraft equipped with sensors and satellites and attempt to match with seismic data to calculate what the explosion was. Officials said it will be several days before the US has a handle on the actual size of the explosion, payload and the success, or lack thereof, of the test. Bottom line, successful or not, these tests do help North Korea learn and continue to perfect the technology. North Korea's rocket-fueled obsession Senior administration official says one of the the things the U.S. will be trying to determine, is whether the North Koreans tested a uranium weapon for the first time. The past two tests were plutonium. The U.S. and its allies will also be trying to figure out what type of technology and engineering was used to pull off the test and what, if any, help and materials North Korea may have received from other countries, like Iran. In addition to the analysis of data, the U.S. is currently analyzing North Korea's statement. At first glance, the part about using a “miniaturized” nuclear weapon is concerning, because that would mean the North Koreans may have mastered the technology to fit a nuclear weapon on a long range missile which could possibly reach the U.S.. North Korea successfully demonstrated it could launch a long range missile through its rocket launch last December, but questions remain about its ability to aim it towards a long range target or even repeat the launch success. United Nations Security Council members meet Tuesday morning and officials say the American playbook will be pretty familiar. The officials all said Washington will seek a “tough, swift reaction” from the UNSC. Obviously what comes out of the council will depend on what China and Russia will sign on to. But one official said “there is a pretty strong commitment to go with a seriousness of purpose” to the UN. How does the test work? Officials said administration is also looking at what other kinds of sanctions can be slapped on North Korea, probably the most sanctioned entity in the world. They are looking at the playbook for Iran sanctions – shipping, insurance, more sanctions against financial transactions, designations of individuals. “There is plenty to do,” another senior official said.