North Korea is calling off high-level talks with South Korea because of ongoing military exercises between South Korea and the United States, South Korean media reported Wednesday local time.

North Korea's Korean Central News Agency also cast doubt on whether the much-anticipated summit between Kim Jong Un and President Donald Trump could proceed as planned.

The regime believes that the Max Thunder drills between the South and U.S. air forces are a rehearsal for an invasion of the North and a provocative move amid signs of improving ties between the two countries, the South Korean Yonhap news agency reported.

The White House did not immediately reply to a request for comment from NBC News.

"The United States will also have to undertake careful deliberations about the fate of the planned North Korea-U.S. summit in light of this provocative military ruckus jointly conducted with the South Korean authorities," Yonhap reported KCNA as saying.

State Department spokeswoman Heather Nauert told reporters on Tuesday afternoon that the U.S. would "continue to go ahead and plan the meeting" between Trump and Kim. She suggested that the U.S. had been caught off-guard by the Korean report.

The mercurial North Korean leader had "said previously that he understands the need and the utility of the U.S. and [South Korea] continuing in its joint exercises," Nauert said, stressing that the exercises are legal and "planned well, well in advance."

The two-week exercise kicked off Friday. It involves 100 warplanes, including eight F-22 radar-evading fighters and an unspecified number of B-52 bombers and F-15K jets, Yonhap reported.

This is a developing story.