Three days after President Donald Trump and Kim Jong Un shared a warm and fuzzy moment on North Korean soil, the despotic regime accused the U.S. of being "hell-bent on hostile acts" against the secluded nation.

North Korea's mission to the U.N. released the harsh statement Wednesday, saying it was responding to a letter co-signed by the U.S. urging nations hosting North Korean workers to send them back in accordance with global sanctions. The letter was sent last week – a few days before the historic meeting of Trump and Kim – to all U.N. member states.

The Trump administration also has lobbied the U.N.'s North Korea sanctions committee to halt all deliveries of refined petroleum to North Korea, a move put on hold by Russia and China.

Trump made no mention of the letter or the press for more sanctions when he tweeted an offer last week to meet Kim in the DMZ. Trump, who already had scheduled a trip to South Korea, previously held more formal summits with Kim in Singapore and Vietnam.

"What can't be overlooked is the fact that this joint letter game was carried out by the permanent mission of the United States to the U.N. under the instruction of the State Department, on the very same day when President Trump proposed the summit meeting," the statement said.

The State Department, in an email to USA TODAY, reiterated that sanctions remain in effect and the U.S. expects all nations to enforce them.

"President Trump remains committed to the goals he and Chairman Kim set in Singapore of transformed relations, lasting peace and complete denuclearization," the email said. "We look forward to resuming working-level negotiations to make progress towards those goals."

North Korea has been strapped by ever-tightening U.N. sanctions since 2006 as global powers press Pyongyang to end its nuclear and ballistic missile programs.

"It is quite ridiculous for the United States to continue to behave obsessed with sanctions and pressure campaign against the DPRK, considering sanctions as a panacea for all problems," the North Korean statement said, using the acronym for the Democratic People's Republic of Korea. It added that the world must keep vigilant "against deliberate attempts by the United States to undermine the peaceful atmosphere that has been created on the Korean peninsula in no easy way."

The tone was much friendlier just days ago, when Trump became the first U.S. president to set foot in North Korea during the hastily arranged meeting with Kim.

"It's just an honor to be with you and it was an honor that you asked me to step over that line," Trump told the North Korean leader. "And I was proud to step over that line."

Trump added that it was "a great day for the world."

Trump had said the duo would merely conduct a brief handshake, but they met for almost an hour. Afterward, Trump said each leader would provide a team of negotiators for talks aimed at persuading Kim to dismantle his nuclear weapons program.

Foreign policy analysts warned then that the border meeting won't mean much unless it leads to progress on a deal to dismantle North Korea's nuclear weapons programs. Still, hopes were raised.

Harry Kazianis, with the Washington, D.C.-based Center for the National Interest, said the meeting could "set the tone for ... carving out a path toward lasting peace on the Korean Peninsula."