As President Donald Trump continues to ramp up trade pressure on China, Beijing may be "less motivated to cooperate" with the U.S. over sanctions against North Korea, an expert told CNBC Wednesday.

"China has been taking steps to relax its enforcement of sanctions even before the trade tensions with the United States flared up," according to Scott Seaman director of Asia at political risk consulting firm Eurasia Group.

But as the trade war between the world's two largest economies drags on, China could find more reasons to relax its enforcement of sanctions against North Korea, he said.

The U.S. and China are currently embroiled in a trade spat, with each side slapping additional duties on each other in the past few months. The U.S. has imposed extra tariffs on $250 billion worth of Chinese imports — with Trump threatening to impose levies on all $500 billion worth of goods from the Asian giant. Beijing has retaliated with additional tariffs on $110 billion worth of U.S. imports.

"The more that Trump puts pressure on China in the economic front, it stands to reason that the Chinese will be less motivated to cooperate well on North Korea. Even if U.S. keeps sanctions in place — which is the expectation — there is a lot of room for China, Russia and other countries to simply ease up on enforcement," Seaman said.