U.S. Secretary of State John Kerry is in South Korea where he will be discussing security issues amid fresh fears of North Korean belligerence.

Kerry arrived in Seoul on Sunday from Beijing and will see top South Korean officials on Monday, less than a week after South Korea's spy agency said North Korean leader Kim Jong-un ordered his defense chief executed with an anti-aircraft gun for complaining about the young ruler. The allegation, if true, adds to concerns about the erratic nature of Kim's rule, particularly after Pyongyang claimed last weekend it successfully test-fired a newly developed ballistic missile from a submarine.

Those actions come despite a recent U.S. diplomatic overture to North Korea to discuss resuming denuclearization talks that have been stalled for the last three years. (AP)