US President Donald Trump has criticised South Korea after Seoul declined his request to assist the United States in its military operation against Iran. Trump said the decision prompted Washington to scale back military drills with the key US ally, while questioning why the United States should continue spending billions of dollars to defend South Korea from North Korea. Speaking to reporters in the Oval Office, Trump said he had personally called South Korean President Lee Jae Myung and asked whether Seoul would help with the Iran conflict.