The United States has requested that the World Trade Organization (WTO) schedule a meeting on October 14 to approve a U.S. request for authorization to take countermeasures against the EU. Pursuant to WTO rules, the WTO will provide this authorization automatically at that meeting. The EU is not allowed to retaliate against WTO-authorized countermeasures. The tariff increases will be limited to 10 percent on large civil aircraft and 25 percent on agricultural and other products. The effective date of the additional duties is October 18, 2019.
The Federal Register Notice listing the HTS that will be subject to the additional duties can be found here