In 1979, North Korea renegotiated much of its international debt, but in 1980 it defaulted on its loans except those from Japan. By the end of 1986, hard-currency debt had reached more than US$1 billion. It also owed nearly $2 billion to communist creditors, principally the Soviet Union. The Japanese declared North Korea in default. By 2000, taking into account penalties and accrued interest, North Korea's debt was estimated at $10–12 billion. By 2012, North Korea's external debt had grown to an estimated US$20 billion despite Russia reportedly writing off about $8 billion of debt in exchange for participation in natural resources development. Besides Russia, major creditors included Hungary, the Czech Republic and Iran.