The United Nations Security Council imposed new sanctions on North Korea today that aim to cut the Asian state's annual export revenue by more than a quarter in response to Pyongyang's fifth and largest nuclear test in September. <br/><br/>The 15-member Council unanimously adopted a resolution that cuts North Korean coal exports by 60 percent with an annual cap of 400.9 million US Dollars on sales. It also bans the export of copper, nickel, silver and zinc.