Several days before the important summit between U.S. President Donald Trump and Chinese leader Xi Jinping in Beijing, the United States imposed new sanctions on a number of Chinese firms over ties to Iran, CNN reports.

On Friday, the State Department imposed sanctions on four firms, three of them based in China, over their involvement in providing satellite images that it said enabled Iran to strike U.S. troops in the Middle East.

Meanwhile, the U.S. Treasury Department on Friday designated 10 individuals and companies, including several based in China, which it said helped Iran obtain weapons and materials needed to build ballistic missiles and unmanned aerial vehicles. “Today’s actions hold Chinese-based companies accountable for their support to Iran,” Secretary of State Marco Rubio said in a statement on Friday. “The United States will take all necessary actions at its disposal to target third-country entities and individuals supporting Iran’s military and defense industrial base.”

The United States recently imposed sanctions on several Chinese oil refineries in connection with purchases of Iranian crude oil, prompting retaliatory measures from China, which ordered companies not to comply.

Beijing’s Foreign Ministry has repeatedly said it opposes “unilateral sanctions not based on international law” and will defend the rights of Chinese citizens and companies.

Trump is expected to visit China next week.