China accounts for nearly all of the isolated North's trade and energy supplies. Beijing has imposed limits on oil sales and cut deeply into the North's foreign revenue by ordering North Korean businesses in China to close, sending home migrant workers and banning purchases of its coal, textiles, seafood and other exports.
Imports from the North shrank 81.6 percent to $54 million in December while exports to the isolated, impoverished country contracted 23.4 percent to $260 million, said a spokesman for the Chinese customs agency, Huang Songping.
The U.N. Security Council has steadily tightened trade restrictions as leader Kim Jong Un's government pressed ahead with nuclear and missile development in defiance of foreign pressure.
Beijing was long Pyongyang's diplomatic protector but has supported the U.N. sanctions out of frustration with what Chinese leaders see as their neighbor's increasingly reckless behavior.
Despite the loss of almost all trade, the impoverished North has pressed ahead with weapons development that Kim's regime sees as necessary for its survival in the face of U.S. pressure.
China has steadily increased economic pressure on Pyongyang while calling for dialogue to defuse the increasingly acrimonious dispute with U.S. President Donald Trump's government.
Pressure, but not too much
Analysts see North Korea's need for Chinese oil as the most powerful economic leverage against Pyongyang. But Chinese leaders have warned against taking drastic measures that might destabilize Kim's government or send a wave of refugees fleeing into China.
Chinese leaders have resisted previous U.S. demands for an outright oil embargo but went along with the latest limits.
Under restrictions announced Jan. 5, Chinese companies are allowed to export no more than 4 million barrels of oil and 500,000 barrels of refined petroleum products to the North per year. They are barred from supplying its military or weapons programs.
Chinese officials complain their country bears the cost of enforcement, which they say has hurt businesses in its northeast.