North Korea’s trade deficit with China hit a historic high in the first half of 2017 as the nation’s exports to its closest ally slipped 24 percent, in a sign that UN Security Council resolutions are having an impact, according to a South Korean economic research institute.

A report on China-North Korea trade from January to June this year, published Monday by the Korea Institute for International Economic Policy, pegged North Korea’s trade deficit at $810 million. This was 2.8 times higher than last year’s first half — the highest level ever recorded for this six-month period.

The total trade volume between the two countries from January to June weighed in at US$2.5 billion, down 0.8 percent from 2016. North Korea exported $840 million worth of goods to China, down 24 percent from the same period a year earlier.

The North’s imports from China, excluding crude oil, on the other hand, reached US $1.66 billion. That was 18 percent higher than the previous year. Crude oil wasn’t included in the study because China’s customs authority omits the data in calculating bilateral trade, the research institute noted.