Acting White House Chief of Staff Mick Mulvaney has called North Korea's possible resumption of nuclear and missile testing a "breach of trust" between Washington and Pyongyang, adding that further tests would disappoint the Trump administration.

Mulvaney spoke to Fox News on Sunday and said there was a "general understanding" that the North's nuclear and missile activities would not continue as long as the two sides were continuing talks.

Despite the breakdown of the recent summit in Hanoi, Mulvaney highlighted U.S. President Donald Trump’s good relationship with North Korean leader Kim Jong-un and said he can foresee the two leaders sitting down for a third meeting at some point in the future.

Mulvaney also responded to critics of the pace of the denuclearization negotiations, saying people who thought it would be easy to get a deal that satisfied both sides "don't understand the complexities of the issue."

The acting chief of staff's remarks come after Pyongyang said that it is considering whether to continue nuclear talks with Washington and maintain a moratorium on missile tests.

[Photo : YONHAP News]