Treasury Secretary Janet Yellen said she sees no signs that Russia is currently skirting U.S. and European sanctions over the war in Ukraine by tapping its deepening ties with China.

“I’ve not seen evidence that China is providing Russia with any significant workaround for our sanctions,” Yellen said in an interview with CNBC Thursday. “Chinese banks do a lot of business with the West. They care very deeply about their relationship with the U.S. and European financial systems, and they seem to be very cautious in their willingness to do business with Russia.”

The Treasury chief declined to comment on what the Biden administration might do if it did see signs of Beijing helping Moscow to get around the welter of sanctions put in place by the U.S. and its allies. Commerce Secretary Gina Raimondo earlier this week vowed to vigorously enforce export controls on Russia and said the U.S. would be on guard against Chinese semiconductor companies that might try to get around the sanctions.

“China does buy Russian oil, but I think that our sanctions are limiting Russia’s ability to sell to China and other countries,” Yellen said earlier Thursday in an interview webcast on Washington Post Live.

She also said on CNBC that “conceivably there could be some partial relief for Russia through that channel but I don’t think that anything will happen through China—or at least I am not seeing any evidence of it—that would significantly mitigate the crushing burden of what we’ve done.”

European Limits

China hasn’t joined in sanctioning Russia’s economy over its neighbor’s invasion of Ukraine, and has instead examined tightening its economic ties. Beijing is considering buying or increasing stakes in Russian energy and commodities companies, such as gas giant Gazprom PJSC and aluminum producer United Co. Rusal International PJSC, people familiar with the matter said earlier this week.

Yellen said in the Washington Post live event that she didn’t expect European countries to follow the U.S. in banning imports of Russian fuels, citing the region’s dependence on Russian fossil fuels.

“We recognize that not all countries are in the same position in terms of their ability to cut off shipments of oil and gas from Russia,” she said.

Yellen also reiterated that the Biden administration is prepared for further steps against Russia amid the continuing invasion.