China will take “all appropriate measures” to defend its legal interests in response to a U.S. trade investigation into China’s intellectual property practices that has aroused tension between the world’s two largest economies. The U.S. Trade Representative formally announced the investigation on August 18.

The investigation is the administration’s first direct measure to be taken against Chinese trade practices, which the White House and some U.S. business groups say “are damaging” American industry.

China’s Commerce Ministry said in a statement that the move sent the wrong signal to the world, and would be condemned by the international community. “The United States’ disregard of World Trade Organization rules and use of domestic law to initiate a trade investigation against China is irresponsible, and its criticism of China is not objective,” a Ministry Spokesman said. “China expresses strong dissatisfaction with the United States’ unilateral protectionist action,” he added, warning that China would take “all appropriate measures and resolutely defend China’s lawful interests.”

U.S. Trade Representative Robert Lighthizer formally initiated the investigation under Section 301 of the Trade Act of 1974, which allows the U.S. to unilaterally impose tariffs or other trade restrictions on foreign countries. It was frequently used in the 80s and early 90s, but was rarely used since the World Trade Organization (WTO) came into being in 1995. According to the Chinese government, such investigations run counter to WTO rules.