On September 8, President Trump issued five proclamations under Section 338 of the Tariff Act of 1930 that revise the 50% tariffs announced in July (and which took effect on August 22) on certain Canadian goods and prohibit imports of selected Canadian alcoholic beverages, dairy products, and motor vehicle-related goods. The White House described the measures as a response to Canada's continued and additional trade actions affecting US exports. The tariff-list changes take effect September 15, while the import bans take effect September 29.

These actions apply in addition to any existing tariffs imposed under Section 232 of the of the Trade Expansion Act of 1962 and will apply to all covered goods regardless of whether they qualify for preferential treatment under the U.S.-Mexico-Canada Agreement (USMCA). Covered goods imported before September 29 but not yet entered for consumption, or withdrawn from warehouse for consumption, remain subject to the applicable 50% duty. The proclamations authorize U.S. Customs and Border Protection (CBP) to issue implementing rules, guidance, and HTSUS modifications. Each import-ban proclamation also provides that, if a ban is invalidated for a covered import, the corresponding 50% Section 338 duty applies to that import.

In a September 8 statement, U.S. Trade Representative Jamieson Greer described the measures as combining "targeted import bans" with "a calibration of the underlying Section 338 tariffs." USTR stated that the revisions target selected Canadian sectors while removing certain non-sensitive goods from the tariff lists. USTR also announced that the President directed USTR and the General Services Administration to remove $50 billion in Canadian-origin products from GSA Multiple Award Schedules.

Summary of the five proclamations

• Alcohol tariff list modification: Effective September 15, adds to the 50% tariff list numerous cheese classifications, certain fats and oils, hides, leather and fur products, and several recreational motorboats to the 50% Section 338 tariff list. It removes bulk whiskies and bulk liqueurs and cordials in containers larger than four liters. See the proclamation here.
• Motor vehicle tariff list modification: Effective September 15, adds to the 50% tariff list products including certain cheese, paper and paperboard, iron and steel structures, aluminum bars, profiles, tubes and pipes, base-metal articles, golf carts and small-engine passenger vehicles, an outboard motorboat category, furniture, mattresses and lamps. It removes salt, Portland cement, certain sugars, paper household and hospital goods, refined lead, specified switchgear assemblies, and fishing-rod parts and accessories. See the proclamation here.
• Alcohol import ban: Effective September 29, prohibits the importation of specified Canadian alcoholic beverages, including packaged beer, wine, cider, sake and other fermented beverages, and broad categories of packaged distilled spirits. Some tariff lines are covered only when imported in direct-to-consumption packaging, as specified in the annex. See the proclamation here.
• Dairy-related import ban: Effective September 29, prohibits the importation of specified Canadian whey and modified whey products, molasses, and non-alcoholic beer. See the proclamation here.
• Motor vehicle-related import ban: Effective September 29, prohibits the importation of Canadian motorcycles and similar cycles with reciprocating internal-combustion engines over 800 cc. See the proclamation here.