US President Barack Obama has extended the economic sanctions against North Korea for another year amid lingering tension over the North's nuclear and missile programs. In a statement to Congress, Obama said the extension is aimed at dealing with North Korea's "unusual and extraordinary threat to the national security and foreign policy of the United States constituted by the existence and risk of proliferation of weapons-usable fissile material on the Korean Peninsula." The US has extended its sanctions on North Korea, also subject to international sanctions, each year in June, according to South Korea's news agency (Yonhap). Tension persists on the Korean Peninsula following the North's failed rocket launch on April 13, prompting the UN Security Council to tighten sanctions on Pyongyang. South Korea and the US have called on North Korea's new leader, Kim Jong-un, to stop its policy of provocations and improve its human rights record, but Pyongyang has responded to the call with threats.