South Korean President Moon Jae-in called the cancellation of next month's landmark summit between President Trump and North Korean leader Kim Jong Un  "very regrettable and unfortunate" and urged the two leaders to talk to each other directly.

Moon issued the statement after convening a late-night emergency meeting Thursday at the Blue House with top security aides and Cabinet members in response to Trump's abrupt cancellation of the scheduled June 12 summit in Singapore, USA Today reported.

Moon said that establishing enduring peace and the denuclearization of the Korean peninsula are "historic tasks that cannot be abandoned or delayed."

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The Trump-Kim talks would have been the first meeting between a sitting U.S. president and a North Korean leader.

The cancellation appeared to take the South Korean leader by surprise. In an initial response, Moon's spokesman, Kim Eui-kyeom, told reporters, "We are trying to figure out what President Trump's intention is and what it's exact meaning is."

Moon's top press secretary, Yoon Young-chan, quoted the South Korean president as saying it may be difficult to resolve the sensitive and difficult diplomatic issues through traditional means of communications.

"I hope (the countries) will resolve such issues through more direct and close dialogue between their leaders," he added, according to the Yonhap news agency.

In a letter to Kim released by the White House, Trump said he decided to cancel the meeting "based on the tremendous anger and open hostility displayed in your most recent statement."

It came hours after a North Korean official, Vice Foreign Affairs Minister Choe Son Hui, called Vice President Pence's recent remarks comparing the reclusive nation with Libya as "ignorant" and "stupid," according to the North's official Korean Central News Agency (KCNA).

Pence had said North Korea could end up like Libya if it doesn't make a nuclear deal with Washington. Libyan dictator Moammar Gadhafi gave up his nuclear program in a deal with the U.S. and Britain in the early 2000s but was overthrown and brutally killed by Washington-backed rebels in 2011.

United Nations Secretary-General António Guterres said he was "deeply concerned" by the cancellation of the summit.

North Korea, meanwhile, demolished its Punggye-ri nuclear test site on Thursday as it earlier said it would do ahead of the summit. All six of North Korea's nuclear tests have been held at the site.

Before Trump canceled the summit, North Korea said a nuclear showdown with the U.S. could again be possible, responding after Trump said Tuesday that his meeting with Kim might be delayed or even canceled.