When imports enter a country they normally have a tariff or a tax. So for example: when you are purchasing an item from France it’s more expensive because of a duty that the importer had to pay for it to come in. When a Trade Agreement is negotiated there is an elimination of that tax then the import comes in freely and the item may be less expensive than one you could purchase in the United States. If too many of those items are coming in then there may be concerns that there needs to be protection of that industry.