North Korea has cancelled high-level talks with South Korea scheduled for later in the day and is also threatening to pull out of a summit with the United States due to ongoing military exercises between the US and South Korea.

Key points: North Korea calls drills "provocative military ruckus"

North Korea calls drills "provocative military ruckus" US says it's unaware of any threats to cancel summit

US says it's unaware of any threats to cancel summit "Max Thunder" exercises involve US and South Korean air forces

North Korea's official Korean Central News Agency (KCNA) called the US-South Korean "Max Thunder" air combat drills, which it said involved US stealth fighters and B-52 bombers, a "provocation" that went against the trend of warming North-South ties.

"This exercise, targeting us, which is being carried out across South Korea, is a flagrant challenge to the Panmunjom Declaration and an intentional military provocation running counter to the positive political development on the Korean Peninsula," South Korea's Yonhap news agency quoted KCNA as saying.

"The United States will also have to undertake careful deliberations about the fate of the planned North Korea-US summit in light of this provocative military ruckus jointly conducted with the South Korean authorities.

"The US should make efforts to create an atmosphere for mutual respect and confidence before dialogue, not resorting to a foolish farce that may reverse the good trend created with much effort."

Bombs are dropped by US B-1B bombers, F-35 stealth fighter jets and South Korean F-15 fighter jets in drills over the Korean Peninsula last August. ( AP: South Korea Defence Ministry )

Sorry, this video has expired Suspended Korea talks could be a sign the North is panicking, analyst Peter Jennings says

The US State Department said it did not have any information about the threats to cancel, and planning for the summit was continuing.

"Kim Jong-un had said previously that he understands the need and the utility of the United States and the Republic of Korea continuing in its joint exercises," State Department spokeswoman Heather Nauert told a briefing shortly after the North Korean announcement.

"We will continue to go ahead and plan the meeting between President Trump and Kim Jong-un."

White House spokeswoman Sarah Huckabee Sanders said the United States would examine the North Korean statement "and continue to coordinate closely with our allies".

Last year's "Max Thunder" drills involved US Air Force F-16 fighter jets. ( Reuters: Lee Jae-Won )

The two Koreas were set to hold a meeting focusing on plans to implement a declaration that emerged from an April 27 summit, including promises to formally end the Korean War and pursue "complete denuclearisation", the South's Unification Ministry said.

The Pentagon said the May 14-25 Max Thunder exercises were routine and defensive in nature.

A spokesman said the exercises would take place at Gwangju air base and would be "at a scale similar to that of the previous years".

Last year, Max Thunder involved about 1,500 US and South Korean personnel flying aircraft including F-16 fighter jets, according to a US Air Force website.

Sorry, this video has expired US State Department defends South Korean military exercises, says summit plans haven't changed

South Korea says North understood drills would continue

Any cancellation of the summit, the first meeting between US and North Korean leaders, would deal a major blow to Mr Trump's efforts to score the biggest diplomatic achievement of his presidency.

He has raised expectations for a successful meeting even as many analysts have been sceptical of the chances of bridging the gap due to questions about North Korea's willingness to give up a nuclear arsenal that now threatens the United States.

Joshua Pollack, of the Middlebury Institute of International Studies in California, said Pyongyang appeared irritated by the US administration's vow to maintain sanctions in spite of North Korean concessions.

"The North Koreans want a change in tone from the US, and at least so far, they're not hearing one," he said.

South Korea's National Security Office head Chung Eui-yong said in early March, after meeting Mr Kim, that the North Korean leader understood that "routine" joint military exercises between South Korea and the US would continue in spite of a warming of ties.

This was widely considered to be a major North Korea concession, though Pyongyang never publicly withdrew its long-standing demand for an end to joint US-South Korea military drills.

US Secretary of State Mike Pompeo said on Sunday the United States would agree to lift sanctions on North Korea if it agreed to completely dismantle its nuclear weapons program, a move that would create economic prosperity that "will rival" that of South Korea.

Sorry, this video has expired Last month Kim Jong-un became the first North Korean leader to walk across the border between the North and South. (Image: AP)

AP/Reuters