The United States has flouted trade rules with an inquiry into intellectual property and China will defend its interests, Vice Premier Liu He told U.S. Treasury Secretary Steven Mnuchin in a telephone call on Saturday, Reuters reported quoting Chinese state media.

The call between Mnuchin and Liu, a confidante of President Xi Jinping, was the highest-level contact between the two governments since U.S. President Donald Trump announced plans for tariffs on up to $60 billion of Chinese goods on Thursday.

In his call with Mnuchin, Liu, a Harvard-trained economist, said China still hoped both sides would remain “rational” and work together to keep trade relations stable, the official Xinhua news agency reported.

U.S. officials say an eight-month probe under the 1974 U.S. Trade Act has found that China engages in unfair trade practices by forcing American investors to turn over key technologies to Chinese firms.

However, Liu said the investigation report “violates international trade rules and is beneficial to neither Chinese interests, U.S. interests nor global interests”, Xinhua cited him as saying.