North Korea has accused U.S. Secretary of State Mike Pompeo and other American officials of "antagonism" towards Pyongyang, warning there will be challenges in the two sides' negotiations for denuclearization.

In a statement released by its foreign ministry on Wednesday, Pyongyang said it would be difficult to expect an improvement in their bilateral relations or progress in their leaders' denuclearization efforts so long as such antagonism persists in Washington.
 
Amid apparent confusion over Pompeo's recent remarks on Iran, during which he initially said some 80-plus percent of the North Korean economy is sanctioned before correcting himself, Pyongyang said it was an "outright challenge" to their leaders' joint statement issued after their first summit in Singapore last year.
 
In response to Washington's recent one-year extension of sanctions on Pyongyang, the statement said the North will not surrender to the U.S. sanctions.

The fresh criticism comes amid growing hopes for the resumption of negotiations, with U.S. President Donald Trump and North Korean leader Kim Jong-un exchanging personal letters after a months-long stalemate.