The United States is "not willing to wait for too long" for North Korea to take steps toward denuclearization, U.S. Ambassador to the United Nations Nikki Haley said on Wednesday.
The North noted that they returned remains of USA soldiers who fought in the Korean War to the US last week. The station had been used to test major long-range ballistic missiles and satellites.
"As long as the U.S. denies even the basic decorum for its dialogue partner and clings to the outdated acting script which the previous administrations have all tried and failed, one can not expect any progress in the implementation" of the terms of the North Korea-U.S. joint statement, including denuclearization, a North Korean Foreign Ministry spokesperson said in an English-language statement carried by the country's official Korean Central News Agency.
Kim and Trump promised to work to end North Korea's weapons programs at their summit in Singapore, but the two countries have been struggling to reach a detailed accord to meet that goal.
But, following the meeting, US intelligence officials said they believed North Korea was "deceiving" the USA, saying the regime was bolstering production for nuclear weapons at "multiple secret sites" in recent months. "However, the USA responded to our expectation by inciting worldwide sanctions and pressure against the DPRK", the statement read, using an acronym for North Korea's official name.
North Korean Foreign Minister Ri travelled this week to Iran, where President Hassan Rowhani told him the United States could not be trusted after the Trump administration reneged on a 2015 deal to lift sanctions in return for curbs on Iran's own nuclear programme.
National security adviser John Bolton earlier this week said North Korea had not begun the progress, while U.S. envoy to the UN, Nikki Haley, said Washington was "not willing to wait for too long" for the North.
North Korea called out the U.S.' "shameless and impertinent behavior", according to a press release out Thursday via a foreign ministry spokesperson.
In the meantime, both Koreas are seeking an end of the Korean War.
South and North Korea technically remain at war as the Korean War ended only with the armistice treaty.
"The idea that we're going to relax the sanctions just on North Korea's say-so, I think, is something that just isn't under consideration", Bolton said.
The summit held in Singapore marked the first time Kim Jong-un had met a western leader.