A layer of complexity underlying the saber-rattling in North Korea is Pyongyang's growing trade relationship with China, said John Park of Harvard University's Belfer Center for Science and International Affairs.
"It is increasing dramatically," Park told CNBC's "Squawk Box" on Thursday. "For North Korea, they might feel emboldened that they have capabilities and something that makes the South Koreans and U.S. in terms of offers for negotiations less attractive at this time."
On Wednesday, the U.S. said it would soon send a missile defense system to Guam following the North's repeated threats of a nuclear attack on American and South Korean interests. U.S. Defense Secretary Chuck Hagel called the situation a "real and clear danger."