China's exports to North Korea jumped an annual 20.9 percent in the first three quarters of 2017, customs data showed.

From January to September, Asia's largest economy exported $2.55 billion in value to the pariah state, the data showed, according to Reuters. Imports from North Korea during that nine-month period actually fell 16.7 percent, according to the data, and so the total trade figure only saw a 3.7 percent increase, Reuters said.

Of note, both exports and imports between the two nations fell in September from the previous month, according to the data: Exports to North Korea sank from $315.97 million to $266.35 million, and imports from North Korea fell from $288.29 million to $145.82 million.

The figures come as much of the world, including the United Nations, calls for tight economic sanctions on the rogue nation. The government in Pyongyang is paying for a rapidly expanding nuclear weapons program, and it has verbally threatened several countries with attack.

Last month, Beijing announced its intention to restrict trade with Pyongyang on several key items, including textiles, seafood and petroleum products, in compliance with U.N resolutions. Chinese President Xi Jinping's administration has also banned mainland lenders from doing business with North Korean clients.

The rising pressure comes amid a tense war of words between North Korean ruler Kim Jong Un and President Donald Trump, which has stoked fears of military action on the Korean Peninsula. Last week, a U.S. nuclear-powered aircraft carrier conducted drills with South Korea's navy in an exercise aimed at showing off Washington's defense capabilities.