North Korean leader Kim Jong-un has warned about the build-up of US forces. (AP PHOTO)North Korean leader Kim Jong-un has warned about the build-up of US forces. (AP PHOTO) Credit: AAPNorth Korean leader Kim Jong-un says Pyongyang has allocated strategic assets to respond to the build-up of US military forces in the south and vowed to develop additional military measures, the state media KCNA reported. He added North Korea "will undoubtedly develop additional military measures" to prepare to respond to the build-up of US forces, without elaborating further. North Korea has been tightening military ties with Russia and has been supporting Russian President Vladimir Putin's war in Ukraine by sending troops and artillery, according to South Korean officials.