The United States and North Korea have reached a holding pattern in denuclearization talks as both sides seek the upper hand ahead of a key New Year's address by leader Kim Jong Un and a second summit between Kim and U.S. President Donald Trump next year. But criticism out of Pyongyang has been emerging as the North pushes back against U.S. refusals to ease crippling sanctions as a means of breaking the deadlock.

On Sunday, the North repeated its demand that sanctions be removed, with a Foreign Ministry-affiliated think tank warning that a failure to do so "will block the path to denuclearization on the Korean peninsula forever."

The North has repeatedly pushed the U.S. for a reciprocal and incremental approach to denuclearization. It repeated that mantra Sunday in its Foreign Ministry statement.