New U.N. sanctions targeting North Korea's key exports will help curtail funding for its nuclear and missile programs, but they may not bring an end to leader Kim Jong Un's nuclear ambitions and could be hard on ordinary people, a high-profile defector said in an interview.

North Korea will suffer "a heavy blow" once the new sanctions are thoroughly implemented because they block exports of coal and other mineral resources, a major source of revenue, said Ri Jong Ho, 59, who formerly managed funds for the country's leadership as a senior member of the secretive Office 39.

North Korea is expected to lose up to $1.7 billion a year under the latest sanctions adopted by the U.N. Security Council on Aug. 5, according to Ri, who now lives in the United States and responded via phone and email. This amounts to over 80 percent of what he views as North Korea's "actual" annual export revenue.