Senators at a hearing questioned the effectiveness of US efforts to get China the North's main trading partner to use its economic leverage against the North.
North Korea has stepped up its missile tests, and this month conducted its largest nuclear test explosion in spite of tough UN and US penalties imposed in March. That's fueling worries that North Korea is moving closer to its goal of a nuclear-armed missile that could one day strike the US mainland.
Administration officials testified that North Korea's coal exports, mostly to China, generate more than USD 1 billion in revenue for the North annually and account for about one-third of all export income.
Coal and iron exports are allowed under UN sanctions if the exports are determined to be for "livelihood purposes," and not for generating revenue for weapons programs. That provision is intended to prevent sanctions from hurting ordinary North Koreans; China is suspected of trying to exploit it.
More From This Section
In a new sign of US willingness to target companies in other countries that deal with North Korea, the Justice Department on Monday charged China-based Hongxiang Industrial Development Company and four executives with conspiring to evade penalties for providing financial services to a North Korean bank under sanctions.
A South Korean think tank, the Asan Institute for Policy Studies, said in a report last month that Hongxiang supplied aluminum oxide and other materials that can be used in processing nuclear bomb fuel.