President Donald Trump has asked his country’s top trade official to review China’s practices regarding intellectual property.
The move was incremental, but could eventually lead to the US imposing sanctions.
Mr Trump is trying to balance working with China on relations with North Korea, with his "America-first" trade views.
The China Daily newspaper earlier said the move could "poison" relations.
Mr Trump returned to Washington to sign the order, which authorises US Trade Representative Robert Lighthizer to explore whether to undertake a deeper so-called Section 301 investigation.
If such a probe occurs and finds against China, the president could unilaterally impose tariffs, sanctions or other trade restrictions to protect US industries.
The initial review is expected to take months.
Donald Trump has long railed against the massive US trade deficit with China.