U.S. President Donald Trump said Wednesday he will still insist on the denuclearization of North Korea following Pyongyang's threat to cancel a planned bilateral summit with Washington.

"We haven't been notified at all," he said at the White House, in response to reporters' questions about the North Korean threat to cancel his talks with Kim Jong Un.

"We haven't seen anything. We haven't heard anything. We'll have to see what happens," he said. Asked whether he will still insist on denuclearizing North Korea, Trump said, "Yeah."

Earlier in the day, White House spokeswoman Sarah Huckabee Sanders said the United States is prepared for "tough negotiations" with North Korea even while it remains hopeful for the anticipated summit.

"We're still hopeful that the meeting will take place and we'll continue down that path, but at the same time we've been prepared that these could be tough negotiations," she said in an interview with Fox News.

[Pool photo, Getty/Kyodo]

"The president is ready if the meeting takes place. If it doesn't, we'll continue the maximum pressure campaign that's been ongoing," Sanders added.

North Korea earlier Wednesday threatened to cancel the summit between leader Kim Jong Un and U.S. President Donald Trump, slated for June 12 in Singapore, in comments denouncing Washington's call for its denuclearization.

"If the U.S. is trying to drive us into a corner to force our unilateral nuclear abandonment, we will no longer be interested in such dialogue and cannot but reconsider our proceeding to the DPRK-U.S. summit," state-run media quoted Kim Kye Gwan, first vice minister of foreign affairs of North Korea, as saying.

DPRK is the acronym of the North's formal name in English, the Democratic People's Republic of Korea.

Kim Kye Gwan is one of the key officials who have long been engaged in negotiations with the United States.

On Wednesday, North Korea cancelled a ministerial-level meeting with South Korea planned for the day, criticizing ongoing joint military drills carried out by Seoul and Washington for undermining a recent inter-Korean thaw.

At their summit last month, Kim Jong Un and South Korean President Moon Jae In issued the Panmunjeom Declaration calling for "complete" denuclearization on the Korean Peninsula as well as efforts to declare a formal end to the 1950-1953 Korean War.

(Kim Jong Un at a facility thought to be related to nuclear development in North Korea)
[File photo, KNS/Kyodo]