Washington (CNN) The US, South Korea and Japan agreed this week to shift a planned flight of at least two nuclear-capable B-52 bombers so they would not fly over the Korean Peninsula, according to two US defense officials.

The decision was made in the wake of North Korea's objection to US military exercises in the region and a suggestion from Pyongyang that the upcoming summit between Kim Jong Un and President Donald Trump could be at risk.

North Korea threatened to cancel the planned summit between President Donald Trump and Kim Jong Un scheduled for June 12 in Singapore, saying the US should carefully consider the fate of the upcoming meeting, in view of what it calls "provocative military disturbances with South Korea," North Korea's state news agency reported early Wednesday local time.

Officials said Friday it was not clear to them whether the decision to shift the route of the aircraft was in response to Kim's statement but noted the move was part of an effort to try to ease the prospect of North Korea being able to claim the US was engaging in provocative behavior.

The officials insist the bomber missions, which have been going on for several years, are not considered military exercises.

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