Given the remarks by a Chinese Foreign Ministry spokesman, Beijing is staying the course in its relations with Pyongyang despite North Korea’s Feb. 12 nuclear test. Spokesman Hong Lei was quoted as saying that the Chinese government had made no change in its position on North Korea though it had signed up to new U.N. sanctions against the nuclear test.

He made no departure from the policy China had been maintaining toward North Korea when he called for a dialogue among the parties concerned. He said to reporters, “All parties should work to reduce tensions and bring about a turnaround on the Korean peninsula.”

The official policy line notwithstanding, China shows signs of tightening the screws on its ally in the wake of the nuclear test. One of them is a news report that China had stopped shipping crude oil to North Korea in February.

China reportedly exports 30,000 tons to 50,000 tons of crude oil to North Korea each month. Quoting customs data, however, Reuters said in its recent dispatch from Beijing that China stopped crude oil shipments last month, for the first time since early 2007.

If the suspension of crude oil shipments was intended to be a warning against Pyongyang, it would be one of the strongest yet. Crude oil is the largest commodity by value that is supplied to North Korea under Beijing’s aid program, as noted by Reuters. At $100 per barrel, Reuters said, China’s crude shipment would have amounted to around $380 million last year.

Another news report, this time by Yonhap News, indicated China was sending a warning to North Korea when it inspected the restaurants Pyongyang runs in China. Teams of customs and food and drug officials inspected the North Korean restaurants located in China’s northern provinces and Beijing, Yonhap said, adding that the inspections were unusual, given that China had in the past turned a blind eye when the restaurants were cutting corners with regard to immigration and other rules.

Moreover, David Cohen, the U.S. treasury undersecretary for terrorism and financial intelligence, sounded an optimistic note about China’s action against North Korea. He said on his recent trip to Beijing, “We’ve heard nothing but the strong (Chinese) intention to implement the U.N. Security Council resolution.”

Now the moment of reckoning is apparently coming to North Korea, which will have to offer negotiating terms for ending its nuclear program if it does not want sanctions from China.