The United States has indefinitely suspended joint military exercises with South Korea, the Pentagon says, following a promise made by President Donald Trump at his North Korean summit this month.

The exercises affected included Freedom Guardian, which had been scheduled to take place in August, and two Korean marine exchange programme training exercises, Pentagon spokeswoman Dana W White said.

Mr Trump apparently surprised the US’s Asian ally South Korea as well as the US military when he announced the cancellation of joint war games on June 12 following his meeting with North Korean leader Kim Jong-un in Singapore.

Repeating North Korean arguments, Mr Trump said the games were “provocative” to Pyongyang and added that they were “very expensive.”

He also speculated about the eventual withdrawal of 28,500 US troops from South Korea.

Their suspension was regarded as a major win for Pyongyang – which for its part committed to denuclearising the Korean Peninsula – as well as for regional superpower and North Korea ally China.

“In support of upcoming diplomatic negotiations led by Secretary of State Mike Pompeo, additional decisions will depend upon North Korea continuing to have productive negotiations in good faith,” Ms White said.

Last year 7500 US soldiers and 3000 South Korean troops took part in the Freedom Guardian exercises, which the Pentagon has always maintained are purely defensive.

-AAP