North Korean leader Kim Jong Un said a U.S.-South Korea joint military exercise could "ignite a war" and called for the rapid expansion of Pyongyang's nuclear capabilities.

Kim Yo Jong, a senior official on the State Affairs Commission, called South Korean President Lee Jae-myung’s push for improved ties a “pipe dream,” according to a statement published by the Korean Central News Agency. She accused Lee or trying to create an “amicable image” while hosting a large-scale military exercise with the United States.

North Korea is stepping up criticism of South Korea's new President Lee Jae Myung as he prepares for his first summit with U.S President Donald Trump, calling Lee's efforts to engage with Pyongyang a "pipedream".